"UMPlayer (Universal Multimedia Player) is the multimedia player that fills all your needs. With dozens of advanced features and built-in codecs it can handle any media format, and can play Audio CDs, DVDs, (S)VCDs, TV / Radio cards, YouTube™ and SHOUTcast™ streams and even incomplete or damaged media files."
UMPlayer is a new cross-platform SMPlayer fork. Since it uses Mplayer, it can play most video formats and comes with some very interesting features. For instance, it supports CSS skins so it's very easy to theme. For now, there are just a few themes available but more should be available soon.
Here's an example of a UMplayer skin:
Another interesting feature is that it allows you to search, play and save YouTube videos straight from its interface. However, this seems to be broken for the moment, most probably because YouTube changed something once again, breaking Mplayer.
UMPlayer also comes with ShoutCast support and a huge list of radio stations so if you're missing this being removed from VLC, try UMPlyer. You can find this under Tools > ShoutCast.
Other features include: audio and video equalizers, take screenshot of running video, find subtitles on OpenSubtitles, audio & subtitles delay adjustment and many more. Check out the UMPlayer features page for more info.
Overall, UMPlayer has a great potential, but it's a bit buggy for now. For instance if I play a video, open the equalizer and close it, the video starts from the beginning. I've found a few other minor glitches but overall it looks pretty good and you should definitely give it a try.
Download UMPlayer (available for Linux - .deb and .rpm, Windows and Mac OSX)
Update: UMPlayer is now available in the main WebUpd8 PPA as well as in a stand-alone PPA (UMPlayer only).
Thanks to rAX for the tip!