You can see in the technet forums that you have the following options
answered, no replies, helpful

http://social.technet.microsoft.com/Forums/en/categories/ 

and you need to present the forum statistics on the right side ... like in MS forums

Good idea

Good idea

Just trying to extend that feature request. Mark as solved when users says thank you. And another one option. How about add granulation "thank you" on integer values -1, +1, +2, +3 (rating top 100 most useful users will be available with that option)?

Also for humor forums more suitable instead of "thank you" use "funny" and "not funny".