Throwing in some ideas...

INDIAN:
SAFFRON @ Circular Road (back of Boat Quay) / tel: 6536 5025
Tiffin Room @ Raffles Hotel
Rang Mahal @ Pan Pacific Hotel

INDONESIAN:
House of Sundanese Food - 55 & 55A Boat Quay / tel: 6534 3775

ITALIAN:
Sistina, Michelangelo's, Original Sin (veg) - all three in Holland Village: Jalan Merah Saga, Block 43-44 / tel: 6476 7782, 6475 9069, 6475 5605
(PS Many other food options and bars available in Holland Village - 5mins walk from the restaurants on Jalan Merah Saga.)

cheers