I sell six figures of sponsorships each year on programmer-oriented properties and have been through a similar situation to you in the past. My email is in my HN profile so I'm happy to give you some context specific pointers over email, including things I'd rather not say here.

In terms of general advice I can give here:

- I've always found Adsense to perform poorly the more intelligent or technical the audience is. Adblocking is one issue, but essentially sophisticated audience == less likely to engage with weakly targeted ads (except retargeted ads, but that's another story).

- A community site that's so popular has great potential to get a small subset of the audience to pay for some sort of status symbol or internal advertising. See Reddit.

- Depending on what the topics are, job advertising could be lucrative if done right and promoted internally in the right way.

- If you want to take baby steps, consider introducing some BuySellAds units and selling your own ad space through them. You get control over your pricing and if you have an audience an advertiser is interested in, things can work well, especially if you can sell a site wide sponsorship type thing on a monthly basis.

- Do you have e-mail access to your community's members? There could be a goldmine there if it's treated properly. Email CPMs are way higher than the Web.

- Ditto but for having a podcast the community listens to. Podcast CPMs are even higher, but this is an entire project in its own right.

- If you're in the right topic area, boutique networks like http://adpacks.com/ might work well for you. In my experience the CPM isn't particularly mindblowing, but it should be better than Adsense and little work for you.