This has been brought up multiple times... Ideas for the forums should be taken here, or here. I believe that a forum search is going to be included in AGv3. (I'm not 100% sure, so don't quote me.)
The irony here is that this topic has been repeated over 50 times already. (Yes, I bothered to count.) Over 80 if you count the time when we did have a forum search but it was so inaccurate you'd be lucky to find what you were looking for, making this the most repeated topic in the history of Armor Games. (If not, user search beats this as king of commonly suggested features, and this has been implemented in the AG3 closed beta.)
The developers for Armor Games are busy working on Armor Games v3 and won't have time to change anything in this version (v2) that isn't site-breaking. No one knows what the forums will be in AG3 or if a forum software has been chose for AG3, but it should include a forum search because this is the most commonly suggested feature.