I'm finding this quite an interesting thread, thanks for sharing guys. I've used adsense for ages though I'm finding revenues are less these days that what they were before - maybe people are over familiar with adsense and switch off like the way banners were all the rage then click throughs declined?
At anyrate one tool I found useful that I'd like to give to you all is
OpenX which used to be known as phpMyAds. In the old days you'd install this as an ad server yet nowdays you can set up a free hosted account with them, subject to certain page view limitations - but I guess 100 million views a month will cover most site owners needs!
What I like about the system is that you can create ad fields that incorporate different kinds of content. I've run banners direct from advertisers together with ones from affiliate marketing companies and adsense in the same ad space on rotation. The variety seems to help keep users from getting bored and also allows you, as an owner looking to monetise your site, to see which set up is attracting the most attention and keep optimising your site around that.
Has anybody tried using Kontera or a similar service? I'm wondering whether their format produces any consistent results and/or beats adsense?