Useful Zip tool
As more and more software migrates to the Web as a service (known in IT-speak as SaaS), here's a neat free site. Krun.ch will produce compressed files of the material you upload. What I can find on the Web indicates the developer isn't into any funny business with adware, spyware, etc.
Windows users looking for another good utility should check out Total Commander. This is one of the best file management utility programs ever invented for Windows. It's shareware and well worth it. It includes Zip and FTP.