I guess this thread is as good as any other for these comments, hopefully they help the devs:
1. check out EAC. it uses plugins to do track lookups, and I believe the service is free to EAC, (as it should be). I never understood why winamp would pay for gracenote when free services evolved that were just as good and money was tight.
freedb is the obvious one.
CTDB (cuetools) is another, both come with EAC.
This plugin verifies your rips against CTDB database, and submits new CDs to it.
It can also serve as a metadata plugin, providing access to MusicBrainz, Discogs and FreeDB metadata via CTDB. CTDB replicates Musicbrainz database hourly, Discogs and FreeDB - monthly. In addition to direct discid search, it supports the same fuzzy search algorithm as Musicbrainz, and also uses it for Discogs and FreeDB data, increasing the chance that correct metadata will be found.
I have had that plugin offer me different results from different providers, and I pick the one I like best, which is great.
EAC also allows other plugins, including paid for ones, to be installed / used.
2. the reason I have never used picard / musicbrainz apps is b/c they spam a lot of musicbrainz specific fields into one's tags, and I don't like that, esp since some apps will use those tags for sorting and so on over, or instead of, the obvious ones you can easily see and edit.
let me clarify that I have np with musicbrainz as a source for normal tags, which is what EAC inserts, I just don't want winamp to insert MB specific tag fields/frames that I don't want, or at the very least have the option to opt out of those frames being inserted.
3. EAC will parlay the metadata it find into album image lookups, and I almost always find my art with it. it looks to me like it searches via web searches, like google, but of specific sites. just a guess. mp3tag also has image lookup.
4. it would be a really great idea to use a system that does use these multiple sources, and also does its own thing. what I mean is a system that adds a tag for the md5 hash value, audio fingerprinting, degree of confidence comparisons and so on...
what I am suggesting is you could do a lot beyond just metadata lookups, but as a byproduct of them. exact file matching, audio fingerprint comparison (good for eliminating dupes as well as metadata lookup), and adding a tag with the hash so the analysis of the file need only be done once.
winamp could also allow users to opt in to a system where winamp creates its own DB, and social network where users can share the metadata of their own collections, meaning not just a freedb clone, but kind of like winamp cloud without the music, so that users could say "here is my stuff, look at it" or compare ratings, and that could serve as a music recommendation engine.
so anyway, just throwing it all out there.