For everything we're still missing at TMMN, GH Forums nicely fill the gap. The Mega Ran album can also be found there.
And as for more Doujin/Fan works, lemme see what I can gather together: OCRemix, to get the obvious choice out of the way. World Out THR Project. These guys are awesome! "THR Project" literarily means "Three Hours Rockman". R-MEGA. Contributor to THR. Episodes & Melody (Azell). Nice and calm remixes. For some reason, the artist likes to incorporate the Cheetahmen theme in almost every track. CocoRoco Refuge
There used to be a a couple more artists out there, but sadly the internet has eaten up their webpages already...