I currently do not have the data plan but was wondering if BeeJive or something similar would work? If it does even tho I don't have the data plan does it take from my minutes or text messages?
The only times AT&T charges instant messages for data are:
When downloading an IM client (e.g. AIM, Yahoo IM, ICQ, etc.)
When updating an IM client
When adding/removing/updating contacts
When changing IM preferences
BlackBerry Messenger is an exception - it uses data
Bottom line: your IM's are treated as SMS messages except for BBM.
EDIT: These are the rules for individual IM clients. For an all-in-one client like BeeJive, it may in fact use data and NOT be treated as SMS messages like the above.