VLC, our favourite video player for the Mac (and a great player for both Windows and Linux), is releasing a big new version soon, for which you can grab the release candidate right now. It comes with a completely overhauled interface on OS X, with a more iTunes-like library view, not to mention support for Blu-Ray rips and native full screen in Lion.
The Windows version won't see as many obvious changes, though it will have a 64-bit version once version 2.0 reaches stable status. Both iOS and Android should see official VLC releases as well, once 2.0 comes around. If you're a Mac user and want to try out the shiny new version (or if you're using another OS and just want to see what's changed under the hood), click here to download the release candidate for your platform and check out the full changelog here. Note that you can't update to the new version with the RC; you'll have to install it separately.