Sometimes you battery get so low and you need to charge it up quickly and be on your way. You don't mind gaining a little percentage of charge.
Well, I guess you best bet is to switch of the phone and let it charge. That works fine. But did you know a little percentage is lost switching of the phone and on. (yeeeaaaah)
So a more conservative way is to but the phone in flight (airplane) mode. Or turning Mobile network off (Blackberry users)
Putting your phone into airplane mode turns off all of the wireless radios inside, so while you won't be able to receive calls, use data, or use GPS, you also won't be fighting background processes that use those radios for power while your phone is plugged in. The end result is your phone will charge a little faster, and you'll walk away with a bit more power in your battery than you would otherwise.
Of course, you could get a similar effect by just turning your phone off (sans power required to shut down/start up), but this is a bit easier.
Let's know what you think....