sonic1764: SC1, SC2, SC3
x15 jOkeZ oN U: Challenge Maps (Mansion, and Course one)
Yah I Hit That: Chinese challenge map
TM Clerical: Pixel / Challenge Map
sora1kg: Portal Map, Super Mario 64 Map and IQ Test.
Those are my top 10 ever, in no order although I could. After those 10, put whoever you wan't.