I noticed that some of the file types that fb2k support (mostly via third-party components) don't have their own type icons (SACD, MIDI, RealMedia, AMR, AC3 etc), so I made this for some of them that I use.
I don't know if it's any good; I could make more of these things if you'd like it. They're all in the default style of the existing fb2k icons, and all would include 16*16, 32*32, 48*48 and 256*256 sizes.