We now have the following:
After Burner 20th Anniversary Box:
http://vgmdb.net/album/4992
Rail Chase Original Soundtrack:
http://vgmdb.net/album/26773
SEGA Motorcycle Music History:
http://vgmdb.net/album/14928 (Only Enduro Racer though as we already had the rest)
Also Vermilion and Rent-a-Hero official soundtracks, though VGMDB doesn't seem to have it listed.