Correct me if I'm wrong but isn't there 256mb of internal storage? I havde 140mb left and if add up all the apps under "manage applications" its only 70mb. Which gives me 210 total. So where is the other 40? Btw I'm rooted with custom rom if that matters.
android software maybe? its like computer hard drives - even when you start with a new one theres always some room taken up already due to drivers n software n such
Use Terminal Emulator and type the following to see how much space is used up where (no need to su: so folks on a stock phone can do this too):