TinyExpander

Tiny Expander is a very light-weight archive decompression tool. It allows you to extract different archive formats, including Zip, 7Z RAR, TAR and others.

The app reminds me a lot of The Unarchiver. The graphical user interfaces look very similar, and Tiny Expander seems to work just as well.

There are only a couple of settings that you can change in this app, and that is perhaps its weakest point. If you open the application, you will be able to set it to extract archives to a custom folder (instead of the same folder where they were located). To do this, you have to check the corresponding box and then double-click on the path to change it. Below that is another check box that makes Tiny Expander reveal the expanded items in Finder when it is done. At the bottom is the last setting. It allows you to change what happens after an archive has been expanded. The only available option is to remove the package.

In my testing, Tiny Expander did a great job of expanding a multi-part RAR file. It then successfully removed the files and showed me the expanded file. It is a free tool, so you can't really ask for much more.