Collectorz.com has a decent suite of apps for managing MP3s, DVDs, CDs and so forth. At present, I'm only using the Music Collector for my CDs.
For ID3 tag manipulation, I have found that Tag & Rename is one of the best out there. I'm properly cataloging my 4600 MP3s with this tool and it works great. V1 and V2 ID3 tags supported.
Once you get everything organized, I've found that MusicBox, edna, Ampache, and MP3 Server Box are very nice server apps. I can provide links if needed.
-SUO