If your forum has on an average 2000 to 5000 hits per day, then you will be able to earn in double figure per day...
The ctr for forums is typically very low when compart to pure content sites. If you get a lot of traffic (like w/ this forum) you can still make good money though. You just need sheer volume to make up for the low ctr. Why a low ctr? Forum members don't click the ads, only lurkers do. Forum members account for most of the traffic when compared to non-members.
Successful Adsense campaigns on forums are achievable. It relys heavily on your ad placement and forum topic. For example, PureFTA (see sig), is a niche site for free to air receivers, and we have a higher CTR than most because the ads are super targeted, linked to direct sale pages of recievers etc.
forums have the worst click rate among all cms.. Number of impressions will be high but the amount of click will be very low. So it all depends on the content of your site that will decide how much you will earn. ..:: Peace ::.. Jeba
DP is ranks something like 460 and the rumor says that it's earning around $10,000/month. Keep that in perspective.
DP earns a several grands a day!!! I agree that forum has extremely low CTR, but it has high loyal visitors who coming back to visit it regularly, again and again. There're many ways to take advantages of this unique feature of forum.
Well if you want to make forum just make it but if you want to earn also real money from it like at least $20 per day than get at least 10.000 uniques daily to your forum and push them register, and don't blend the ads with your forum but make them SHINY so everyone can see them , also put them better in places where they can be clicked by mistake,
Forums may have the lowest CTR but also bear in mind that forums are also one of the websites with the most number of return visitors (in the form of forum members who log on everyday). It can still be very lucrative if you are able to carve out a niche for yourself and attract members to your forum.
Depends on what you call as " Famous " ... If you have traffic and activity on forum then you will money off it !!
This is kind of like asking how fast a baseball can be thrown, there are a lot of things the answer depends on. My advice is to just go ahead and try AdSense instead of sitting around speculating.