When it launched in 2003 the concept of automatic-content-targeted-ads was unknown to me I think it was original. In fact it turned out to be very profitable and easy. I think it was a big breakthrough because it allows webmasters to focus on building sites and leaves the ad-matching work to their system. Before that the concept of CPM ads was well known, you get paid that much for 1,000 pages views. But the CPM ad networks I knew of were not contextual, so it was boring ads to the visitor compared to what adsense ads could now display. I have known about adsense at the end of 2003 by chance, so it was luckily early registration for me, but is there something new now today that I don't know of? Is there a good contextual ad-matching network for CPM ads and CPA ads? Or something else?
I think Adsense still remains one of the leaders in the ways to make money online. It's still very reputable and well known. A lot of people still use Adsense, more than any other PPC network. I still think however that it will be the leader for a while to come.
Nothing. THe big advertisers tend to gravitate towards the big networks, which is Adsense. I'd try media.net or chitika, but nothing comes close to adsense.
There have been a lot more affiliate opportunities that have come out since then, and there are other services you can use to run ads on your websites and blogs.
I was kind of thinking on the same lines. But, there is nothing close that we can compare to adsense, when we say 'user targeted ad network'. I wonder if Facebook would ever venture into this, but they have limited data as compared to Google. I don't think that's a possibility. Wordpress recently ventured into this: http://en.blog.wordpress.com/2011/11/29/wordads/, but it was not a great hit. Perhaps, all adsense publishers should aim towards getting a premium account and I think that's the next promotion which will bring a positive change in adsense income for the publishers. But, it's not easy though. I would be interested to see others perspectives on this.