I read Stack Overflow daily at work, and often use it as a resource; I love it. Today I noticed a new sponsor logo — the kind that appears next to the tags — it looks like capital D with a white rainbow shooting out of it on a dark blue background. It might be a silly question, but can the dark blue be changed to a lighter shade? I find that the contrast, compared to the "lightness" of the rest of the site, really affects readability. Honestly, it's like my eyes cannot focus on anything else. Please don't take this as whining, it's really just an honest request/constructive criticism.
Companies use specific coloration to signify themselves, not general concepts. The "blue" color that a company uses in its logo will always be the same shade, as that locks in what that logo is. So it's not going to be that company's logo if they use a lighter shade of blue. I don't believe Stack Overflow gets to be in charge of what another company's logo is, so I don't think they get to change the color "behind the back" of the sponsor.
Consequently, contrast is entirely the purpose of adverts in order to catch your eyes. Not to say it's good or anything, but I suppose it's doing exactly its job, aye?