For me it would be a tie between the cell phone and the mp3 player. The first cell phones were horrifically expensive and and huge, but now they're less expensive and can fit in your pocket. I use it more than my regular phone, though my regular phone is for internet. The mp3 player is an audiophile's best friend and a radio station's worst nightmare. As I grew up in the 80s listening to new wave music, that music became quickly lost in history, but iTunes has them (well, most of them). No commercials and no crap that you don't want. All the music that you want. Forget about Atlanta radio stations.
Many of you are too young to remember life without a microwave, popcorn was popped in hot oil on the stove and tv dinners had to cook for 40 minutes in the oven.
This has to be one of my favourites, the USB Rocket Launcher I can shoot Missiles at the Wife while she's watching Eastenders (UK soap opera) ha ha ha
The MicroProcessor Unit. Although it was only JUST invested before I was born. Without that - no CC fuel injection, no mobile phones, no MP3 players, no broadband.
rohypnol.... j/k... seriously, for me personally probably home PCs/internet for the world in general I suppose it has to be some major medical breakthrough or similar...
