What kind of celebrity site? If it's naked celebrities then some kind of "How to pick up girls" product would probably convert. If it's a celebrity diet site then go for lose weight ebooks. If it's a celebrity hairstyles site then some ebooks about hair care... Put yourself in the position of the people who visit your site. What are they looking for? What do they need? What are their desires? Then it'll be easy to know what to market to them.
You haven't answered the question yet: What kind of celebrity site? You have to tailor your offers to your visitors. If your visitors are young(ish) women then swimsuits might be a good one (although I didn't know you could get those through Clickbank...). You should probably split-test as well. Think of a few offers which your visitors might be interested in, rotate them (get a script to do this probably), and see which converts the best. Edit: Did you mean your site is pictures of celebrities in swimsuits? Then your traffic is probably young men, and so you should go for things which might appeal to them. Six Pack Abs, perhaps, or some 'how to meet women' guide. As I said, try a few and see which works best.
If it's a celebrity lifestyle blog, the visitors might be interested in clothing and the latest fashion in order to look like their favorite celebrity.
I don't know about you, but if I owned a celebrity site, I'd probably advertise seduction/dating related products, and maybe some of those "how to make a woman orgasm" products if the site is mostly about female celebrities/models. I guess it just depends on your exact niche (sub-niche?) in the "celebrity" niche.