It will be fantastic to play Real Audio with fb2k if we have plugin~

The newest RealAudio format is AAC, you just have to change its container. DtDrive (i think thats its name) can do this.

Problem with RealAudio and RealVideo is that the decoders arent open as they are with other encoding technologies such as AAC. Its illegal to just somehow tie in the RealPlayer .dll's to Foobar200. Only way is if you know someone with the will and time who wants to reverse engineer the decoder to make an open source version.