Apple Newton MessagePad
It looks like a child's toy now, but the O2 XDA (2002, also known as the HTC Wallaby) felt pretty groovy at the time: it managed to combine a colour PDA with a proper phone, web browsing, email and a touch-screen interface, and it was solid enough that you could use it as a weapon to bludgeon your enemies to death. 2005's XDA IIi was a veritable cornucopia of connectivity: three-band GSM, GPRS, Bluetooth, MMS, SMS, Infrared and 802.11b - but reviewers slammed the Windows Mobile operating system, which was far from intuitive. 2007's iPhone ground Windows Mobile into the dust.
Short, sharp video clips are everywhere thanks to services such as Vine, but Polaroid got there decades before: its Polavision came out the same year as Star Wars (1977) and enabled you to record quick video hits. Unfortunately it came out just before Betamax and VHS did the whole video thing much better.
If you've encountered powerline networking - moving data via your home's electricity cabling - you've probably seen it in the form of HomePlug, but while the HomePlug Powerline Alliance has been around for 13 years the CEBus standard was developed a full sixteen years earlier. Unfortunately it wasn't very quick: average data transfer speeds were around 7Kbps. Today's Powerline kit (pictured) is almost 1,000 times faster.