James beat me to it – they are non-specific ads generated by Google based off what the big G believe is most relevant.
That can be based off the page content, or ‘interests’ which G works out from various things about you/your connection/your search history, or remarketing from third party sites. For example, we have been fiddling with some office stuff so currently I am seeing ads for VOIP phones wherever I go online! Dell and Amazon are quite persistent on that front.
Hopefully the G ads wont be about for too long as its just ‘backfill’ – any any specific annoyances post it up and we will look at it as the whole point is not to be one of those sites with several video ads, overlay ads and an advert over an advert about advertising :)