We currently have a good thing going with Plura, which lets us generate some money without ads. It doesn't pay as well as ads, and its a new company so it might not last, but so far it seems to be a sustainable solution
I'm more worried about Facebook phpDiplomacy in that regard, it's currently running on 1 year of free sample Facebook hosting, but when that runs out I'm not sure what the plan is. I guess since they already have ads built into Facebook it won't be so bad to add them over there
Regarding the layout etc, it's true that I want to keep the forum integrated into the site. We have forum.phpdiplomacy.net for development discussions but I don't think that'd work as well for main phpDiplomacy chat
The other issue is that phpBB and vBulletin all use far more resources than my dinky little forum script. This forum loads in just a couple of well optimized queries (1 query if you don't have a thread open), while profiling phpBB and vB I found that they executed dozens of them. Even less busy sites which run fully featured forums need dedicated hosting, e.g. playDiplomacy which needs a dedicated Xeon with heaps of RAM (though that's in part due to some careless coding
We can do with only a small trickle of income for server fees when using Dreamhost's shared hosting, but if we wanted dedicated hosting we'd certainly have to move to advertising. Keeping performance up is priority #1 for me right now, because the number of page hits and visitors per day has doubled since July, and we were already pushing the limits of what a shared account can do (Dreamhost are a great host in this regard)
A hypothetical; would people rather have a full forum with ads, which may feel fairly separate to the site itself, or minor improvements to the current integrated forum without ads?
Another hypothetical; does anyone have any web hosting which they don't use much, which they would be able to use to share some load (things like images, maps, etc)?