WinRAR is archive tool mostly focused on RAR format but also supports common archive formats.

IZArc is a utility that will decompress tons formats like ZIP and RAR.

ExtractNow is a simple utility that allows you to extract multiple archives quickly and easily.

The Unarchiver is a much more capable replacement for "Archive Utility.app", the built-in archive extraction program on Mac OS X.

Bandizip is a free Zip Archiver. It extracts the most popular compression formats, including Zip, ZipX, 7z, and RAR files.

Zipware is simple and free zip software for Microsoft Windows that supports all major archiving formats.