Actually Apmd is decent as a prepaid as long as you don't mind the hassle with getting it setup in the first place. It takes a little time, but it's worth it with all of the features Ampd offers. I am very happy with it! You can easily check your amount remaining ($$) and download MP3s, videos, ringtones, etc. and all at broadband speed using Verizon network. I even got my phone setup to use as a modem with my laptop. Just plug in USB and connect wirelessly anywhere I have a signal (which is practically everywhere).
I would NOT recommend using Ampd with a service plan!!! Prepaid ONLY! And if you do use them, don't use the fill-up feature to charge your debit or credit card. Just go to Circuit City or Best Buy to buy the fill-up cards or buy them online from someone besides Ampd.