Over at Think *NIX, PRJ2 has a nice post on setting up a system wide key to invoke Org capture. The idea is that even if Emacs isn’t running it will be launched and Org capture automatically called. He assigns this to 【F9】 on all his systems so that no matter where he is or what application he’s using, he’s only one keystroke away from a capture buffer. If, like me, you always have Emacs running, this process should be instantaneous.
The post tells you how to do this on Windows, Unix/Linux systems, and OS X. Even if you have to work on multiple platforms, you can always capture a thought or some data quickly and easily by pressing the same key. Very nice.