Ever had this annoying message given by Windows? "Cannot delete folder: it is being used by another person or program. Close any programs that might be using the file and try again".
Solution: use Unlocker, by Cedrick Collomb. Super tool for unlocking files, processes, determining who or what has files open etc. Of course, there are other tools which perform some of Unlocker's functions as well, but Unlocker does this in a very neat way.