I'm looking for rar file opener
 

I have a registry program that I downloaded, but it is a .rar file. Does anyone know a good free program for rar and other types of unusual extensions?

See Best Free File Archiver/Zip Utility

The one that I've been using for several years is Universal Extractor (it gets mentioned in comments, but never got reviewed.)
http://legroom.net/software/uniextract

Tiny, fast, and no-frills.
It does not compress, it only extracts.
It can extract almost any archive format, plus BIN/CUE CDROM images, and *many* (not all) Inno and Windows Setup installers. (handy if you want to try to run the app as a no-install portable without all that automatic setup for start menu, etc. )

Bone-simple drag&drop interface, automatically creates a new target folder in the archive's directory, but you can browse to and select another target.
(won't work to drop a zip file on a shortcut though, you have to open the app first.)

Give it a try, it's a little treasure.

It's also listed under Best Free Portable Applications -- Best Free Portable File Archiver/Zip Utility.

If you download Rar it will work to open files even after the trial period has ended. You can't make a rar file after the trial period, but if all you want to do is open them, rar will continue to work, you just click through the "buy now" button and it'll extract them.