I've been seeing these quite a lot in the past few days. They're text based ads that attempt to trick you into thinking they're part of the sites navigation, then dump you on a phishing page. They're being served by a couple of ad networks, most commonly Google AdWords
All the more reason to keep an Ad Blocking plugin active.
I only enable Adblock on a site-by-site basis. That way publishers are afforded an opportunity to make money from me, provided they don't annoy me enough to go on the blacklist. Starring James Spader.