I use both www.onesuite.com and www.tel3advantage.com.
They both offer PINless calling (you go online and preregister the phones you'll be using, which allows you to avoid having to enter a PIN). They both allow you to store speed dial numbers where you enter 2 digits + the # sign.
Calls to Bangkok are 5 cents on OneSuite and 6 cents on Tel3. Elsewhere in Thailand it costs about 10 cents on each service.
I use these services it from home as well to most countries. Unlike the "liquor store" type cards, there are no "gotchas" like weekly charges, 5 minute rounding, 50 cents "bong" (connect) charges etc.
If you call certain numbers a lot from your cel, program in the access number to the service, enter a "p" (pause) and then the speed dial number you have stored w. the service. The whole process takes only about 2-3 seconds longer than dialing directly.