depending on what client you want to use, check out this post that i posted at howardforums http://www.howardforums.com/showthread.php?t=654357
it shows a bunch of free IM clients, but you ahve to configure your TCP on the 7100t. if you get that working, please let me know, because i also have tmobile, but cant get the damn TCP layer to work...
this link has a few free games on it http://www.rimroad.com/
here is a link to set up your TCP BlackBerry Internet - MSN/chat/web/telnet/TCPIP - No BES!
hope all that helps... and PLEASE, if you get any of those working, let me know, because i cant.