You can try to google "comparison cell phone plans" or I think the freedomlist website compared ISPs and cellphone plans also.
We're with Cingular and you can try the $39.99 plan where they offered a free camera phone worth $250.(Sony Ericsson z500a) with a 2-yr contract. The plan covers free unlimited calls to any Cingular phone, 450 anytime minutes with roll over, free voice mail, etc. They also offered a 2 months free plus $25 Cingular Visa GC if you have been referred by a Cingular customer. Call their CSR to ask for more details. I referred my friend in August and they got the $60 family plan with 2 free phones, 2 free months and a $25 Cingular Visa card.
I'll be glad to refer you if you're interested in the plan.