Awesome. That's honestly my only "big issue" with this script. Last.FM is so open, that you can end up with multiple entries for the same album solely because people have different tagging standards. Such as "Gang Related (disc 1)" & "Gang Related - The Soundtrack : Disc 1" or a strange entry like "Killer - July, 1st 2008" as opposed to "Killer." The script is good the way it is, but I think allowing a more "finely combed" source would only take it to the next level. Cut out some of the junk and get to the real meat, haha.
As for the three sources I mentioned, RateYourMusic would be a waste of time, because they have no API and no real way to navigate from searches to results and such (or at least a year or two ago when I tried doing a RYM script for MP3Tag's Tagging Framework thing). Discogs implemented and API though a while back, so it's probably the best candidate to look into. No clue on what MusicBrainz offers.
Either way, I eagerly anticipate seeing what you can do with an update to this script, and numerous other scripts of yours.