A company called Opex Wireless runs off of the GSM network, although you'll want to check out for coverage in your area. They offer a plan that is 8.99 then 10 cents a minute per minute, or 14.99 a plan for 100 minutes, but the overages are 45 cents a minute. If you usually only use around 40 minutes then the 8.99 plan would work better for you, you would still need to purchase a phone, but they aren't a ton of money with or without a contract. If you need a link let me know, if not I'll assume you are happy again with Cingular.
