What new trendy **** do you need now?
Are 'downtown circulator' trolley loops still hip, or has that fad passed already? I mean, Cincinnati has one, we'd just be keeping up with the Joneses.
Seriously though, if they wanted to build a public transportation system that was actually useful, they'd be building a subway. Start with a loop that goes from the Airport to the Racetrack to Downtown (convention center, lucas oil stadium, the zoo, the mall, the train station). That alone covers the majority of the places out-of-towners come to Indy for. Then start building branch lines outward, maybe one north to the State Fairgrounds, maybe one south to Indiana University.