If you live in the US, you might find this article handy. It looks at calling plans offered by Cingular, Sprint, T-Mobile and Verizon and does a quick comparison. If you’ve ever tried to do a comparison, you know that it gets confusing pretty quickly. The friendly folks at thewirelessreport.com have done a lot of the legwork using a relatively common scenario: 400-600 of weekday minutes and unlimited night and weekend minutes, nationwide toll-free calling and roaming, up to 500 text messages, at least 2MB of wireless handset-only internet data traffic, voicemail, call waiting and caller ID.
Packages change very often unfortunately but this will at least give you a rough idea that you can then build on for your own needs.
Source: Smartphone Thoughts