best thing to do is have your friends send you a picture message(MMS) but instead of putting in your cell number, have them put in your email address that you have on your phone...this is the only way you will see pictures sent...in return, you will see their cell's "email address"...save the address to CONTACTS for future use. when you want to send them a picture, using you email account, send it to their cell's email address and they will see it as a picture message like they normally would...
i know you wanted to do something other than using the email tool, but this way, once you get everyone's info, is just as easy...plus its free for you to use...AT&T would definitely charge for picture messaging if they did it that way
i think there were som Apps in the AppStore that say they could do what you want, but from what i heard, they arent very reliable