I make about $15 a month on my forum that has about 2,000 posts. These are not google ads or anything, mostly sponsorship and subscription purchases.

That is exactly my experience.
3 Google ads, one at the top, two below the first post and out of over 20 thousand pageviews and over 1000 posts a day I get maybe (on a good day) 5-6 clicks, which makes me (on a good day) one dollar. I never made more than 30$ a month from this particular forum.

I tried everything already, different sizes, colors, placement and styles of ads and nothing seems to work, people simply ignore google ads on my forum.

Then I tried auction ads, people clicked them, but no one ever bought anything. After a week and not a single cent I turned it off.

So, ok, it took me a long time, but now, after well over two years, I realized there is no profit running a forum and I am running it just for fun, while paying all the expenses from my own packet.

I do not even want to think about monetizing it anymore.

^Yeah pretty much, We need some way to get the profits rolling in.

I have about 10K unique visits every day and more than 300K users every month. 1.5 million of page webs and i only have adsense in my forums.

I have 12000 registered users and 180000 posts.

What could be my earnings with this statics?. What do you think?. ( Only to know if i'm doing it bad or good).

Depends what is your forum about, but I would guess, you get somewhere between 5-10 dollars a day, if you're as unlucky as I am :)

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Btw. it's weird that you have 12 thousand reg.users and only 180k posts. I have only 3 thousand users, but 250k posts. It looks like you should give your members more incentive to post.

I don't have a big forum, but I make tons less on my forum than with websites. Me personally, I never click on forums with ads because the content I'm looking for is in the forum or I hit the back button. Other than that, it just all depends on what you do.

I think i have active about 3k or 4k members. 10 dollars / day is good ?

Sounds good average territory. With 3 sites I run getting only 200 hits a day combined brings me in 10 bucks a day. Click thru % is 7.39

I wrote a mod for pixel advertising, similar to http://www.milliondollarhomepage.com/ for a guy about a year ago who reports about $100,000 annually in pixel ad revenue. I mean, they ARE attractive and mesmerising to the end-user. I find myself looking closely at the ads on that site from time to time .

Man! everybody scares me... I doing my boards to get rich! :D