The open-source ads are a wonderful idea and I want to thank you for that great possibility!
Nontheless, I suggest an optimization: Couldn't we add preferred tags to these ads (e.g. python, php etc.) so that they get even more effective? I guess there are probably not enough ads to only base it on these tags, but they could be seen as a matter of preference.
As far as I understand, that is in your interest, too. :)