i'm starting to see a lot of creative maps these days... perhaps they're clever at building them, or they are modding... there's this PetayFanMoFo that i'm friends with on twitter and the SC that continues to post crazy ass races!! search his name on youtube and the SC, he tests and reviews all of those races that are creative like that... dunno if they're any good because i play on the PS3 obviously ...
i was inspired to create a monster truck race because of a few of his creations... his are more big ramps but he does review other crazy creations... here's his job list, friend him to see his posts on races... it's a shame i can't play them...
http://socialclub.rockstargames.com/member/petaypanmofo/games/gtav/jobs?platFormId=1