To be honest, I'm a great fan of SfStats.net, so I'm really excited about this new forum feature!
I have been using your system since the beginning of 2009 and I found these ideas would make your site much useful:
I'm using your site for soccer matches, so primarily I will talk about it.
1. When I check a preview of a league match, I can not see the teams' previous matches in the cups. It would be great to see the teams' previous matches whether these matches were in the national cup or in the international cup. (At present I have to search for the team on a different sub-page to see these results)
2. A database of injured players would help me a lot.
3. Detailed list of goal scorers and players who gave assists would be another very great option.
These are just my first impressions. I guess, you will receive a lot of inputs in the next months, so you have to be selective.
Good luck for your job!
I'm looking forward the developed betpedia.org!