There's a VAST amount of random things people create for Mousehunt, some of which is pretty cool. 

Here's the one that started me realizing there was a world of MH beyond the forums. (Hint: Zugs Tower flowchart.)

Here's a site where someone created a website just to track his collections, but by pictures! (Greyed out for not yet found.)  

Here's a breakdown of farming GlowingG in the labyrinth, and what trap setup is best.