Several ways I can think to reduce bandwidth:
1) Allow all of the options on my CSS maker to be done server side(why send me code I don't look at) http://www.mctrivia.com/bkcssmaker/

2) Fix RSS Publication date bug(well this only reduces bandwidth for my autoplayer)

3) Give option to replace images with text in game boards

4) XML output so your programing customers can write low bandwidth apps for use on Cell Phones and slow internet(this would also let some smart people make real time play possible on this site) RSS feed is already XML output for the game list you just need to fix publication date see 2

5) Use Ajax to replace periodic complete refreshes with refreshing only changed data.