Is there any "rules" about how much can be charged for selling advertising space on a poker-blog? It will of course depend on the traffic for sure. I also thinking of doing the same with a newsletter about poker, again what can I charge for adspace in the letter? Hope some can give some good advice on this one, thanks.
You can charge whatever someone is willing to pay for so you should pose this question to an advertiser that wants to advertise with you. Your customers will determine your market price based off the value they perceive that they are getting based off of your reach, traffic, rank, etc.