I'm getting rid of google's ads and replacing them with something else for 2 reasons:
1) The ads hardly pay anything relative to others, and with the increasing use of ad blockers nation is hardly bringing in 50$ per month as of late 2013 (and costs about 75$ per month to keep up).
2) Google ads are not very forum-friendly, since we have very little control over the content of each page and they're too strict with the content policies. If there's so much as the word "sex" written on a page somewhere I'll get spammed threats to take the ads offline. So after battling them for years now I finally told them go screw themselves and removed their ads.
If the ad revenue can return to its old glory I'd be able to do more event giveaways like I used to with Steam games.
The new ads & changes
The first thing I'm doing is increasing the nation gold cost of the no-ads upgrade, so getting it requires much more contribution to the community (which in turn should attract more new members).
The new advertising network will be Intergi. I've seen it on other forums and it looks pretty good.
I also affiliated with J-list, so there's going to be ads that link to merchandise on their site and Nation gets a cut of those sales.
The last change will be in the location of the ads. I'll be experimenting with different placement to see what performs best, so don't be surprised if you see an ad somewhere there never was one before.