Actually there are quite a few "toboggan" type coaster out there, just about all of them built by the master Swartzkopf. The Jet Stars, Jumbo Jets, City Jets, Jet Star II's, etc., and one last remaining Speedracer in the states, Whizzer at SFGAM.
As for trackless coasters, ride the wild Avalache at PKD for the absolute best "bobsled" type coaster around. Easily blows away Disaster Transport and all the others. Shame it's the only Mack trackless coaster in the states.