Is there a way to prevent my Mac from going to sleep when certain apps are running? Specifically, I'd like it to stay awake if I have Adium on. It will work if iTunes is playing, but once it's stopped, it goes to sleep. The main reason I'm looking for this is because it leaves me looking like I'm online, but I'm not. Sure, I can close it, but sometimes I get away from my Mac and then leave or something, and it goes to sleep. Silly, sure, but there has to be something out there for this.