On sites that show full page ads between page clicks, then at the top it says click here to continue, (like on ign.com), did they just program that themselves or is that involved with whoever they are using to advertise? Thanks!
I think adbrite and valueclick offer them sort of ads. There is some quick information about both of these ad networks here I've personally never used these sorts of ads so I'm not 100% sure if they do offer these sorts of ads, but sure someone had mentioned these 2 networks offering these before. Good luck.
In AdBrite there is a bug I think that I can't click on the "SKIP THIS AD" button because I can't see it :\