Easy one this. For years tech-makers trying to get all their know-how into a single device, and then Apple comes along and does it, causing a collective slap hand on forehead.
The iPhone enables you to make and take phone calls (duh!), serve the internet, play music, watch movies, play games, find your way around and check the weather without ever pausing for breath.
The real killer, of course, has been the Apple iPhone's multi-touch user interface. It's actually made all of the iPhone's nefarious functions properly useable - which is more than be said for most of the applications in some of its rivals.
Hell: Taser C2 with MPH holster
The road to convergence hell is littered with devices that share one common theme - the uncanny ability of tech makers to shoehorn MP3 playback into anything and everything no matter how bizarre. The Taser C2 with MPH holster has to be one of the oddest examples yet.
The Taser C2 is, of course, a non-lethal weapon that can stun anyone who comes close with a jolt of electricity that's enough to incapacitate them while you make a getaway.
Tasers are so 'good', several UK police services (not forces, remember) already use the professional versions to take out hoodies and the odd diabetic, but it's the consumer version we're looking at here.
The Taser C2 is aimed at ladies with a taste for pink, leopardskin and other natty patterns and is offered with a optional MPH holster accessory that can be used to store up to 1GB of MP3 music - so you can bop while you stop the baddies.
Already dubbed the iTaser by bloggers, the Taser C2 sadly isn't available to own in the UK You can buy one Stateside for around $80 (£40)
Heaven: Sony PlayStation 3
If anything qualifies as a home entertainment hub for the 21st Century, then the Sony PlayStation 3 is probably it.
By design the PlayStation 3 is a cutting edge games console, high definition Blu-ray and DVD movie player, audio CD player and a Wi-Fi-enabled internet appliance. Plus you can also use its 40GB hard disk drive to store music, photos and video too.
Compare the PS3 to its rivals in convergence terms and not even the Xbox 360 comes close - largely because the HD DVD drive was only ever included an optional accessory, and now HD DVD is defunct.
Sony's also managed to wrap up all this technology in a pleasingly usable interface and a glossy, understated case design that hints at the power within. We love it.
Hell: Amstrad Em@iler
Now (in)famous for being Britain's most famous entrepreneur, Sir Alan Sugar has also proved to be a woeful judge when it comes to good tech.
Not content with saying that the iPod would be a flop, he also monumentally misjudged the public's appetite for the Em@iler - an internet-connected home that enabled the PC phobic to send and receive emails.
The concept seemed noble enough, but the execution was horrible. The original Em@iler (see, even the name makes you shudder) was a Frankenstein product, marrying a cheap-looking home phone with a wired pull-out QWERTY keyboard and a laughably bad monochrome LCD display. Its successors weren't much better. Why?
The Amstrad Em@iler was a pain to use, not very reliable cost a fortune to run - chiefly because buyers were charged 20p every time it connected to Amstrad to find out if there were any emails. It even served up advertising on its display, adding yet more insult to injury.
Sir Alan Sugar was apparently so convinced that the Amstrad Em@iler would be a success he apparently lost millions trying to make it one - despite all evidence to contrary. Amstrad CEO Bob Watkins even resigned over it, allegedly.
Heaven: Panasonic DMR-EX88 HDD DVD recorder
Hard disk toting DVD recorders are unsung heroes of the great gallop towards convergent devices, managing to do some pretty complicated things in a very sensible and mostly user-friendly way.
The Panasonic DMR-EX88 is a case in point. It manages to combine a 400GB hard disk drive with a CD player, DVD player and DVD recorder, throws in a digital TV tuner with Freeview Playback and then adds a USB port and SD memory card slot.
You can also use the DMR-EX88's huge hard drive to store your digital music library, thanks to its Music Jukebox function and a built-in version of the Gracenote CD database.
We particularly like the fact it also include a 1080p video upscaler, enabling your movies to look nearly as good on a large flat panel TV as proper Blu-ray versions.
Available for as little as £349 online, the Panasonic DMR-EX88 is also a better all-round solution to your AV needs than any entertainment PC you can name, despite sharing many of the same capabilities. It's certainly easy to use and looks great under your TV too.
Hell: Victorinox S.Beat MP3 digital audio player
Many people would consider MP3s to be offensive enough, without having weapons attached, but even the peace-loving Swiss are having a go.
The S.Beat MP3 digital audio player from Victorinox combines 2GB of pocket tuneage with a Swiss Army knife enabling you to listen to the radio or even Ogg Vorbis files while getting stones out of horse's hooves, clipping your toenails or sticking pigs.
Reassuringly Victorinox also sells a version (the S.Beat MP3 Flight) that enables you to remove the MP3 player. This has the benefit of still enabling you to enjoy your music, without being zapped by iTaser-toting WPCs - the knife bit can safely be stowed in your suitcase or simply left at home
Heaven: RIM Blackberry Bold 9000
If you're the kind of person who'd be just too embarrassed to flash an iPhone around in public, the Blackberry Bold is sure to appeal to your outer geek. Why?
Because the Blackberry Bold looks just as credible when it comes to convergence. It packs in full web browsing, super-fast 3G data speeds, GPS satellite navigation, and can playback your movies and iTunes music too.
But the Blackberry Bold also has something the iPhone does not - a credible backstory when it comes to keeping you up to date with the work world - thanks to that hardcore emailers dream - a physical QWERTY keyboard.
Hell: LG GRG227STBATV fridge
A great example of bad convergence tech, the LG GRG227STBA TV fridge takes two previously separate technologies and lumps them together in a way that even now seems rather baffling.
The reasoning behind it seems understandable. Why?:
The kitchen is the busiest and most frequently used part of any home; and the fridge is the most popular item in it;
You'll be able to use the TV fridge to watch cookery programs on its 15-inch display;
It maximises space in your living quarters - making ideal in countries like Korea and Japan, where homes tend to be small.
It's strange then that the TV fridge also leaves out two other options that would actually be rather handy:
A built-in internet connection you can download recipes - you have to hook the TV fridge up to an off-board PC instead.
A personal video recorder (PVR) with chasing playback so you can record your favourite cooking programmes, and watch the really important bits over and over again.
No exploration into the highs and lows of consumer tech would be complete without name-checking Brando - a Hong Kong company that specialises in weird USB peripherals. Highlight on its website include a USB Skype Mouse, which adds a internet phone to the humble PC mouse, the Casio USB Mouse Printer, which throws in a printer. Our favourite - has to be Brando's USB Slippers, which use the Intel invented connection to keep your feet warm in the office. Marvellous, or awful, depending on your point of view.
Which convergence gadget would you praise to the hills, and which would you take out back to be shot? Let us know, write in the comments below!