I just read Shoemoney's idea about measuring IPU. You can find it here: http://www.shoemoney.com/2006/02/01/is-your-website-makeing-what-it-should-be/ I had always worked out income per page request, but I can see why IPU is better. So, I calculated my IPU and it is $0.013, i.e. 1.3 cents per unique visitor to my website. I am just using AdSense and nothing else. Shoemoney says he can get 2 - 9 cents IPU consistently, but I know he uses more than just AdSense. I'm still a bit miffed about the 0.7 cents I'm missing per unique though! What is your IPU? Anyone care to divulge their IPUs for AdSense and other income streams? Do you think that the IPU is a good measure of AdSense success?
It really depends on the site and sector you are in. Even 25 cents per unique visitor seems very low to me - but I target niche sectors. I think it is a useless number unless you are comparing apples to apples.
I do about 30 cents/unique. I definitely think it depends on what you do: affiliate, adsense, or retail. The numbers will vary greatly. UPI is not a new concept. EPV is the normal acronym for it (earnings per visitor), also heard it called a myriad of other things.