unzip-fm -> http://maemo.org/packages/view/unzip-fm/ - Works from File Manager - Just click a zip file and it extracts from where it is...

unzip -> http://maemo.org/packages/view/unzip/ - Can unzip files from console (Xterm) using unzip filename.zip. You can also use unzip -t filename.zip to "test" a file (show contents) before unzipping.

unrar -> http://maemo.org/packages/view/unrar/ - Works from commandline (Xterm) - unrar filename.rar.

There are also 2 graphical utilities (haven't tried any of them):

Xarchiver -> http://maemo.org/packages/view/xarchiver/

File-Roller -> http://maemo.org/packages/view/file-roller/

All utilities are in Extras-Devel so BEWARE (of the baad baaaaad Extra-Devilish boogy man)...