Even though this suggestion seems bad, I'm going to have to agree with you. The site needs more activity. Most of the activity is in the marketplace and I would love to see some of the other subforums get some activity.
Anniversary group + award(2012, 2011 members).
Group + award giveaway. No, not your typical post to win giveaway. Give it to someone that you think would be able to run an active group and not just sell it a month later.
A scavenger hunt. Post clues around the forum and if you find all the clues by a certain time/date, you get an award. 1st person to find all the clues should get some Koins.
Even though this theme is quite new, I say we get a new theme. Maybe not to replace this theme, but as an alternative.
Some new plugins. I would definitely LOVE to see a gambling plugin for the Koins system. I would also love, and I'm sure many others would as well, a username color changer plugin. This has been suggested so many times in the past and I think it should be implemented.
The ability to take a vacation ban. I know what some people are going to say. "Well why don't you just sign out?" For some people, it's not that easy. Forums are distracting, more than you'd imagine. If you're active, you try signing out and not signing back in within the hour. Some people have done it, but some people are just not able to.
Now. This suggestion is going to be a pretty big one and a lot of people are going to disagree with me, but this is best for the forum.
First big suggestion. If you have enough funds to compensate everyone for their awards that they've purchased. I say you revoke everyone's user-owned awards and put only a few up for sale. This will increase value and demand will be higher. Which means you'll be able to sell them for more without any questions. Not only will it increase the value and demand, but the buyers won't just want to give them out to anyone. Maybe the awards purchased will have a purpose. I say 5-15 user-owned awards, max.
Second big suggestion. Once again, if you have enough funds to compensate everyone, I say you purchase everybody's group and put only a few up for sale. There are way too many groups available and the value is way too low for a forum of this size. Every single group has buy-ins but none of them have any activity in their subforums. Even if they do have some activity, it's not much. Whoever wants to disagree with me, go ahead. Even if the group you're in has a ton of activity, it's going to die down. No one joins a group to be active, they join the group for the userbar and that's just not how it should be. I say 10 usergroups allowed.