What would be a great improvement for my site would be a wikipedia content integration. Just like it's working with youtube, you would add [wiki]Metallica[/wiki] to a post and the addon would fetch the content from http://en.wikipedia.org/wiki/Metallica and integrate it into the post. Maybe just the first 500 chars with a "read more" link.
Could that be done? Would pay for that, but due to the fact that we are a non-profit forums, we could affort max. 50$. But maybe there are others which are interested..