X-Keys are a strip of shortcut buttons that you stick on your monitor and assign macros to using software, allowing you to quickly do tasks you do frequently with the push of a single button.
It's pretty neat for people who use programs like Photoshop all day and do macroable things, but my repetitive tasks are harder to program one-button macros for. I mean, I can't get it to IM Chen to talk about video games in the middle of the afternoon, nor can I get it to go poke around in the fridge even though I know I have no food. But hey, when they figure out how to make one of those, I'll be the first in line to buy one. I'm all about efficiency, after all.