I was going to register winzip, but I found the new version of WinRAR to be as good, and do much, much more.
WinRAR is now my backup software, for backing up data onto CD-RW - powerful exclusion and inclusion lists, much better compression, support for file security and streams, recovery records, world class encryption, archive attribute support, etc.
The companies stay in business, because people (often businesses or institutional users) do register software. For this reason, I do pay for quality software that I want to see improved, and I use regularly.