Not sure how late they're open, but I love to have chili crab right next to the Concorde Hotel on Orchard Rd.

Right by the side of the hotel is a row of outdoor food stalls, and the last one is a seafood place that has some great chili crab (or black pepper if you prefer). You can also get cheap beer there in those big bottles. Overall a great place to eat in a casual, street-food type atmosphere...