So my pet peeve with my PowerBook has been accidentally unplugging it when charging and then it’s not charged when I need to take it somewhere. Very annoying. The really annoying part is that I think Apple had a feature to avoid this built in in OS 9 (or 8) but it’s been gone for ages.
I know I’ve looked for an application or utility to do this before, I don’t know how I missed it. But now I found one and it’s called Unplugged! What UnPlugged does is alert you when you unplug the power adapter (and when you plug it back in). And it’s freeware (donations accepted)! It’s probably going to annoy me with the alerts but at least I’ll never be annoyed that I don’t have power! (It supports Growl too).