djoPlayer is a simple and easy to use GUI to MPlayer.
It can read the following formats : DivX 3, 4, 5, Xvid, ASF, WMV, MPEG-1, MPEG-2, MPEG-4, MOV, AC3, OGG... and even DVDs or movies on the Web. It also can read subtitles.
It allows you to activate the PostProcessing very simply, in order to see less of those ugly squares in your video... You can set up some options like the level of PostProcessing or the size and aspect of the subtitles.
It's made with AppleScript Studio. The website is in french for the moment, but the applications are also in english.
What's new in this version:
The 3.4.1 version is for Mac OS X v10.3 only, because AppleScript changed... If you want the version for Mac OS X v10.2, please use the alternate download link.