[mstevens]

One more vote for the Oz instant messenger that comes free on the phone. First, it's free. Second, it's supported by Sprint so if I have problems there's someone to whine at. Third, (as noted above) it has significant battery advantages. Finally, I'm a very casual IM user so installing another app isn't worth the trouble for me.

It might help if you let us know in what way the included instant messaging app doesn't meet your needs. That increases the chances that you'll get a recommendation that's right for you.