Header nofollow link SEO?

[surenot]

I am planning to show ads on the header some like Google!

Title
URL
Description 1
Description 2

The URL link will be nofollow one! Do you think that could cause some SEO issues? Also ad text in will in many cases will contain text URL (non clickable) could that have some negative effects on SEO?

URL anchor link will be nofollow but the anchor text will show URL what about that? I mean showing somebodies URL in above fold content is making me nervous!

[goodroi]

Having a small ad above the fold, that includes the url for another website is usually OK.

If you have a very big ad (or already have 9 other small ads) then you might want to check out this discussion about Google Page Layout Algo [webmasterworld.com...]

If the ad has a large amount of text, it might impact the keyword combinations for your page. If the ad is annoying/distracting it can scare visitors away and that can indirectly impact other SEO issues.