I picked up a pre-paid SIM for a friend yesterday at SingTel.

S$15 for the SIM and included S$18 in credit.
Signed up for a data package- S$7 for 1GB data for 7 days.
If you top up S$10 you get 10 days free incoming calls, and $20 you get 20 days free incoming calls, or...
Pay S$.60 per day for free incoming calls.
Calls are S$.16 per minute and if you dial 019 before country code, there is a list of a few countries which you only pay the S$.16 (local rate) per minute. US and China are on the list, along with a few others.

Hope this helps someone...