I have been a faithful user of Filzip for ages.
www.filzip.com. It hasn't been updated for a while, but it does the trick pretty well. It's free, lightweight, and the interface resembles the classic Winzip one, but it includes a tree view at the left, which is quite convenient (I know, Winzip has it too, but back in the day, it didn't). It even has a (limited) cmd line interface. The only glitches I have found are:
1. Mouser points out that Winzip and Winrar can uncompress many files at once, each in its own subdir. I have found no other program to do this, and sometimes it is so necessary.
2. Sometimes I have problems decompressing RAR archives with "nonstandard" characters on the contents' file names. I resort to command-line unrar.exe in these cases.
3. Some newer programs can read and extract files from ISO CD images. Filzip can't. This is not compression pre se, but it can be useful.
Every now and then I look around for something newer and better, but I keep coming back. I am reading the other suggestions and see if there is anything new under the sun. Right now I'm trying QuickZip and looks good. I'll let you know; I just wanted to add my 2 cents on good ol' Filzip.