It came to me in the shower this morning. I doubt I'll bother doing it so figured someone here might want to bank from it.
Register a load of celebrity domain names in the same format. Eg unofficialjessicaalba.com, unofficialtomcruise.com etc etc About 100 should do it to start with.
Setup a blog on all of them and go on a massive content hunt. Find photos, videos, news articles. Anything you can to seed the content.
Stay on top of it. You want to have every bit of juicy gossip within hours of anyone else.
Do some decent inter-blog linking for maximum SEO boosting and you'll soon see a bunch of long tail traffic (you are writing your own content not just copy/pasting other people's right?)
Stuff like this is massive link bait. You'll get absolutely *tons* of backlinks from people talking about it and you'll also get people commenting on your blog posts like you wouldn't believe. Go Google celebrity gossip and check those sites out if you don't believe me.
Next setup a main aggregator site. Feed all your RSS feeds into it. Add event news, stuff like that. Run a gossip forum. Link from all of your blogs to this site and you pretty much can't fail to rank for masses of celebrity searches.
Even if all you do to monetize this is throw up some adsense and get shockingly poor CTRs this'll still do pretty well.
If you can't afford to splash $1,000 on domains for this then get a fairly generic domain for the aggregator and setup a celebrity name subdomain for each star. It won't SEO quite as well but it should still do pretty well if you keep the content flowing.
SEO/Traffic tips -
Don't forget to submit links to your blogs *everywhere* you can.
For B/C list celebs you'll probably be able to score links on their wikipedia page if you site/content is good enough (I've seen several examples of this).
Usual blog and ping stuff.
Enjoy! If you do try this project drop me a PM and let me know how it works out.