Open Source Adsense
It seems that currently Internet advertising is moving into a new phase, called content sensitive advertising. Google is the main contender in this field with its Adsense and Adwords.
In another unrelated area of the net, Open Source is growing very fast, and in the 3rd corner is Peer 2 Peer software (or shared computing).
What makes Adsense work so well is the amount of people that use it, and the Google name behind it makes it better.
Think what would happen if a lot of small websites were to offer services like Adsense... They would not work. But if they were to join in collaboration, developing open source Adsense like software, they could be a step better.
To really compete, the little players need to work together have the advertising network built over p2p so all the players work in collaboration. The network could be built on trust. So you trust your advertising partners, and they trust theirs etc. etc.
If any one wants to grab this idea and start running, I will gladly be a part of it (not that this is a requirement). The only reason that I am submitting this idea, is that without the power of open source, little me can not compete with the Google giant.