tried the dosa cart today and it was slammin. got the pondicherry and the rava masala dosas and they were both really tasty (he didn't skimp on the spice either). also came with a little soup (nothing like some hot soup in 90 degree heat).
Also,I was wondering where this arepa lady I have heard mention of sets up her cart? I'd search but I have no luck with my chowhound searching.