Save battery by switching to 2G after a few minutes of inactivity I'm looking for an app that'll switch to 2G only after a few minutes of inactivity. The idea seems simple enough, but I can't find it.

JuiceDefender just disables the data connection, and re-enables it every 5-15 minutes. But that's a bit too restrictive for me.
JuiceDefender can do this. It also can turn off data completely, and turn it on every 5 minutes or so to let stuff sync.