Wow, congrats on ten years!
My favorite MobileRead forum section would likely have to be the ePubs part of eBooks formats section. I think that is what first brought me here(a search on how to do something specific in my epub code) and I stayed for all the other cool stuff. The only way I could see it being made better is more thumbnails/examples of what the code does. I love the 'code snippets' topic but really wish all bits of code came with a screenshot of what exactly that code looked like in the epub! Many people do include it but not all and I am a visual person who needs that screenshot to know if that code is one that I would use. I would say a more organized way to show the code would be useful too (so if I have a picture resize issue I can easily find all posts related to it...the search often brings up to many unrelated posts) but I have no idea where to start trying to organize all the information in that one code post, let alone the whole section.
(a close second favorite forum section would be the Reading Recommendations)
Thanks for the contest, and for such a great community!