Knowing which applications to stop Looking at my currently running apps screen, I see many applications by htc and android, probably running the UI, and sync and stuff like that. Is there a list or a site that explains what each app does, so I can decide whether I should close it?
Is there a way to automate some of this? Using Tasker maybe, and a timeout, to close apps that are not recently used by me?
The people over at XDA-developers.com will tell you: you don't need a task killer!

Why? Well you see RAM only uses up energy when you change what's in it, so actually the act of 'cleaning' up costs you more than keeping it in memory.

The only apps I would recommend closing are those that require internet access and/or sync often. This includes various games, social networks and your email.

Update: I would add GPS apps to the list of ones you want to keep an eye on, although these generally have explicit "exit" options, and so don't require killing either.

For the rest, it's best to let Froyo decide for you!