Many moons ago, I registered WinZip, since it was then the de facto ZIP tool for Windows—there was no competition in the graphical world back then that I was aware of.
So I get email from them every once in a while telling me about new versions and suggesting that I upgrade.
But really, for the past several years, it's been amusing seeing what they come up with to put into new versions.
See, zipping is really not rocket science. After a while, you have the basic operations pretty much down, and the application is essentially feature-complete.
So it's fun to see what they grasp at to justify extracting an upgrade fee from their customers. For example, lossless JPEG (re-?)compression, zipping straight from cameras, image viewing inside archives, new encryption methods... all not really part of their "core competencies" IMO.
It's all rather amusing, really.