Task Manager?

[jondaviseffect]

i know that when you hold the home button down when in an application it will end the application instead of "minimizing". is there a way to check which applications are currently running? or a way to end them all?

 

[bradenwh]

If you are jailbroken, download SBSettings from Cydia, and download the Processes add-on along with it.

From now on, using SBSettings, you can view which apps are currently running in the background, and end whichever one(s) you want.

 

[svndmvn]

and if you're not jailbroken, the only apps allowed to work in the background are the stock Apple ones, and usually not even those do.