Any Video formats that render with Alpha Channel? Does anyone know if there are any video formats (besides the HUGE uncompressed avis) that you can render in that maintain the alpha channel? (i.e. for after FX etc.) 

I used to use quicktime, but that's no longer an option.  I know you can render in png. or other image formats, but video is significantly smaller, and I often work on machines with less space &amp; resources.
If you're using OSX you can use its Quicktime support:


Selecting any of the video formats in the Output panel.
In the Encoding panel change the format to Quicktime and select a codec that supports alpha (such as HuffYUV).