Full user review
"Excellent free file archiver"
An awesome program, handling a variety of archive file formats (popular examples include .zip, .rar, .7z, .tar/gz/bz) for a total cost of $0. A bargain, to say the least.
The icons used are a bit ugly, though muchly improved if you use the freeware (not open source, nor affiliated) 7zip Theme Manager: http://www.7ztm.de/
What's more to say? It's free, and it covers a wide variety of file formats. It's lightweight, and it's open source. Also apparently upcoming as of current alpha/beta versions is further integration with Windows 7, namely the taskbar progress bar when compressing/decompressing. Certainly a worthy alternative to WinRAR and WinZip, handling more files than those two as well.