My top five would have to be:
*DVD Decrypter (and SmartRipper--both do the same thing)
*DVD Shrink (don't use it much anymore since i store stuff on an external drive now)
*CCleaner (really does a good job, and it's free--beats the paid programs in many ways)
*PDF Creator (although it does have some toolbars it installs, which I remove--that and MS Office now includes the capabilities of creating PDFs from the Office apps, but it's nice for printing pages from a browser to a PDF for example)
Those are about the top five freebies I use at least weekly, except for Shrink, which I use only rarely, but is still worth mentioning.