I love Portable Apps. A very convenient way to take your tools with you. While they're great for when you're on the road, you know they aren't just for USB drives? You can install them on your hard-drive as well. Need to run two different versions of Firefox? Install one normally, and install the other as a portable. I've been testing sites with a Firefox screen reader called Firevox. Some of Firevox's shortcut keys conflict with my development plugins. That isn't a problem though, because I just setup a portable version on my hard-drive and installed Firevox there. Now I can run Firevox without a problem, and I didn't have to disable any shortcut keys.