Bar these hardware upgrades, the iPhone is much the same as the original - it's got the same 30-pin dock connector on the bottom, it boasts the same 3.5-inch multi-touch display and it runs the same 2.0 iPhone software.
Whether you ponied up £269 for an original iPhone, or you've just unboxed the new 3G version, there are a wealth of extras that you can buy to go with it. From suede flip-cases and headsets to speaker docks and software, we've gathered together our favourite iPhone add-ons below.
The first thing your shiny iPhone needs is a protective case. O2 and Carphone Warehouse shops only carry a limited collection.
You'll find rubberised silicon cases (lightweight, cheap, protect from scratches) and smart leather pouches (too fiddly, hides the actual phone); Blackberry-style holsters (that clip to your belt) and neoprene armbands (designed for sports fanatics). Prices range from £7 to £20.
Search the web, however, and you'll find that there are even more. There are natty suede flip-cases and tough clear acrylic shells.
There are striking mirrored iPhone cases, invisible 'shields' and Luis Vuitton luxury sleeves. There's even a $20,000 18-carat gold iPhone case embedded with 42 diamonds.
There's really no 'best iPhone case'. It depends on what catches your eye. Want something a little different? Try a brightly illustrated vinyl GelaSkin. Or hunt around eBay for the elusive Gold Tiger iPhone Steel Skin.
Proporta headphone de-tangler
You won't know that you need one of these simple Proporta cable tidies. Not at first. Not until you've stuffed your pearly-white Apple headphones into your pocket and, when you've retrieved them sometime later, spent five minutes angrily untangling them.
The Proporta Cable Tidy is a simple solution - it's basically a magnetic clasp that can be clamped around the cable of your headphones thereby avoiding any entanglement. You can buy a pack of two online for £3.
Griffin iTrip AutoPilot
Thanks to Griffin, iPhone owners can now legally pipe their favourite music through their car stereo. The new Griffin iTrip AutoPilot is the first, fully-licensed and 'Made for iPhone' FM car transmitter. It uses Apple's 30-pin dock connector, so it's compatible with every iPod from the 4th generation onwards.
Plug the iTrip AutoPilot into your car's power socket/cigarette lighter, tune it into an open FM frequency and your car suddenly becomes a giant set of speakers.
Track-skipping is controlled via the iTrip itself, rather than by fiddling with the iPhone. Built-in RDS technology means that track names from your iPhone's library will be displayed on your car's audio equipment if it's RDS-capable.
"The AutoPilot is a highly functional, if not stunning, piece of kit," says our own TechRadar verdict. You can read the full review here.
Apple Bluetooth headset
The white headphones that ship with Apple's iPhone aren't bad. The recessed headphone jack on the iPhone 2G meant that owners had to buy an adaptor if they wanted to use their favourite earphones.
But if you want to effortlessly answer phone calls while you listen to music (or watch video) then you need a set of buds with a microphone capsule. Or what about a Bluetooth headset?
Apple offers its own lightweight wireless earphone - a jet-black stick with a single button for answering/hanging up calls.
It's a pricey £79 for the whole Apple iPhone Bluetooth Headset package, but that does include a Bluetooth travel cable and the £29 iPhone Dual Dock.
Tactile feedback for your iPhone
Now this may, or may not work... We haven't seen one yet. But My Touch Keys promises to add tactile feedback to the 2G and 3G iPhones.
My Touch Keys is essentially a plastic skin (much like a screen protector) that attaches to the front of your iPhone. This skin has precisely-cut holes designed to fit over the iPhone's virtual QWERTY keyboard.
This allows you to 'feel' the indentations as you press the buttons. Still don't quite get it? Then hop over to the My Touch Keys website and watch the video.
There are several iPod docks that are compatible with the iPhone - Altec Lansing's T612, Sharp's DKAP2BK and JBL's On Stage III to name but three.
But they all pale into insignificance when compared to Bower & Wilkins' mighty Zeppelin. It might look like a flattened, black rugby ball with a strap-on iPod dock. But the Zeppelin is actually full-blown stereo speaker system in one eye-catching unit.
For hi-fi aficionados, the two bulbous grilles hide impressive speakers, each one consisting of a 25mm tweeter and a 90mm slotted woven fibreglass midrange cone.
Both of these are powered by their own 25-watt amp. And that's not all. There's a 125mm bass driver (that has its own 50-watt amp), not to mention a matching, pebble-shaped remote control.
True, the functionality of the B&W Zeppelin is fairly basic. But you're paying £400 for its oh-so-perfect styling and the professional B&W engineering.
If the B&W Zeppelin doesn't float your boat, consider a smaller, cheaper, 'bedside table' clock radio for your iPhone... The GrooveSnooze from veteran iPod accessorizer Cygnett is a compact speaker dock, charger and clock radio combo.
Plug in your iPhone at night, set the alarm and you can be woken in the morning by either the AM/FM radio or tunes from your iPod library. For deeper sleepers, there's an ear-grating buzzer to shock you out of your slumber.
Despite its small size, the Cygnett GrooveSnooze boasts 10 watts of output per speaker, while the audio is decent enough thanks to the unit's 2-inch bass drivers and dual tweeters.
It's not as good, perhaps, as a dedicated set of speakers (Altec Lansing's T612, for example). But the addition of a clock radio gives it a useful twist. Hunt around and you can buy the GrooveSnooze online for around £40.
Video conversion software
As well as being a decent phone, iPod, web browser, mobile map and games machine, the iPhone is also an excellent video player. The iPhone supports H.264 and MPEG-4 in .mov, .mp4 and .m4v file formats, so if you have a pile of DivX content then downloading some good video conversion software is essential.
For PCs running Windows, try the Videora iPhone Converter. It's a free application that can transcode all manner of video files including DivX, Xvid, VOB and MPEG. Featuring a handy batch conversion option, you can select several video files and leave them converting overnight.
For Mac owners, we recommend iSquint. Like the Videora iPhone Converter, iSquint simplifies the video conversion process. And if it doesn't do everything that you want it to, a more advanced version, called VisualHub, is available for a £13 fee.
Freeloader solar charger
Charge your iPhone for nothing using the power of the sun. The Freeloader 8.0 from Solar Technology is essentially a compact battery with two solar panel 'wings'. The panels convert solar energy into electricity, which can the be funnelled into a variety of portable devices.
The Freeloader is supplied with 11 different connectors to charge your iPhone or iPod, Nokia phones, LG Chocolate/Shine phones, Nintendo's DS Lite and more.
According to Solar Technology, The Freeloader 8.0 "boasts the ability to power an iPod for 18 hours, a mobile phone for 44 hours, a PSP for 2.5 hours and a PDA for 22 hours".
While it can charge an iPhone in real-time, the internal battery can also hold a charge for up to three months. The Freeloader 8.0 is available in classy aluminium or 'look at me!' pink and costs £30. A bigger solar panel (and therefore faster charging) is available if you upgrade to the £49 Globetrotter model.
Kensington Mini Battery Pack
If you have to criticise Apple's iPhone range, you might point the finger at its battery. For starters, it's not easily replaceable - the case is sealed so you can't buy a spare battery cell and swap it out.
This can be a problem if you're travelling and you watch a lot of video or you browse a lot of web pages. Or if you sit there with the GPS activated, happily watching yourself as a blue dot on a Google Map.
As the iPhone is a converged device, you don't just lose your phone when the battery runs out. You lose your iPod, sat-nav, web access, calendar etc.
It's where mobile chargers like the Freeloader and the Kensington Mini Battery Pack come in.
The rechargeable Kensington solution is a compact lithium-ion polymer cell, which can be charged via USB and then clipped to the bottom of your iPhone via the 30-pin dock connector. At the moment, it's a US-only product but you can buy online for $50.
Got any more quirky iPhone accessories to suggest? Drop us an email or leave us a comment below.