You're thinking of something called The Unarchiver:
http://www.fsf.org/blogs/licensing/free-rarv3-extraction
- [Trisquel-users] Free RAR v3 support in File Roller tegskywalker
- Re: [Trisquel-users] Free RAR v3 support in File R... jason
- Re: [Trisquel-users] Free RAR v3 support in File R... em9002
- Re: [Trisquel-users] Free RAR v3 support in File R... tegskywalker
- [Trisquel-users] Re : Free RAR v3 support in F... magicbanana
- Re: [Trisquel-users] Re : Free RAR v3 supp... Michał Masłowski
- Re: [Trisquel-users] Free RAR v3 support i... tegskywalker
- [Trisquel-users] Re : Free RAR v3 support in File ... magicbanana
- Re: [Trisquel-users] Free RAR v3 support in Fi... tegskywalker
- Re: [Trisquel-users] Free RAR v3 support in File R... chris
