Banked curve like Teeside used to have was always awesome, just make sure it's painted / coated with something in case it rains...
Raised sections, drop offs, step-ups, table tops, cross over jumps... all pretty good fun!
Would be good if someone could create an authentic "Whoops" style section like a supercross track, but one where they're fairly shallow so you can do them in 2's, 3's or 4's or just skip across them without too much hassle....