I don't have a site open right now.. But I have always found the best mix is using Adsense and Adbrite. They work well and are both customizable to the forums...Also getting sponsors is good to pay cost if your getting enough hits...The most I ever made a month off of a forum was about 800 bux..But that was with steady sponsors. And we were getting about 10K uniques a day. It had about 30K members. But ive made close to 500 bux on smaller forums with like 5 to 10k members.. It just depends on your forum and the subject matter..Though advertisers love stats... So if you wanna start making ad money I would suggest keeping detailed stats to show as proof..Maybe awstats...I always liked their layout.
Though as always just my opinion...But if your subject pertains to local business..You can easily find someone to talk into sponsoring you for 100 or so bux a month..They just write it off when comes tax time...Just have to get out and talk to people and hustle
Also..dont forget about extending some type of service to your members and have donation buttons...Are the best way I have always found are card draws...You raffle soemthing off costs you maybe 100 dollars pertaining to your forum..And then sell 52 cards at maybe 10 bux each...thats 520 bux - 100 for item 420 dollars to pay for hosting and such..Just have to be creative.. But raffles are great too