A close friend of mine is a punk musician with several albums out, tours across multiple countries and a reasonably large fanbase etc. Not 'super-famous' but famous enough. I know that he was suicidal after a nasty article appeared about him written by some particularly venomous journalists (he had an affair, we all make mistakes - but the disgusting media leeches just couldn't resist could they)... So I know that he's visited this site, at some point last year perhaps, and looked through the mega-thread on hanging (we spoke about it before I registered - it was how I found this site later on).
But if he's actually registered here then I have no idea who he is, and I wouldn't dare want to ask him in person - I doubt he would still be active if he was. That's the price of anonymity though, any one of us could be famous or not famous.
Here's an interesting ethical question. If you were stuck on whether or not to commit suicide, and a member on here was famous (and you were their biggest fan) - if they asked you to commit suicide, would you feel more pressure to do it?