Nah, but I have had text with her.
And he’s super good looking! 
For me, author Susie Moloney, and a bunch of local television journalists.
That’s cool. I was just listening to The Adicts yesterday.
No one. My personality tends to have a shelf life in any event, so maybe there are some famous people out there who I’ve made all the happier today, if only for the fact that they don’t know me. 
In college, one of the people I was close friends with (but lost touch with) went on to become a CEO of a semi-large financial firm in NYC. I saw his name on Linked In and I attempted to add him as a Linked-In contact with a nice note, but he never accepted.
A few years later, when I was between jobs and semi-desperate, I went so far as to send him an email to say ‘hi’ and to ask if he knew of any entry-level openings that his company might be looking to fill. Now, Brian was someone who I’d been to 100 parties with, bought beers for, and had (through our group of friends) numerous adventures and hijinks with.
I never got a response, not even a form letter. I guess I can safely say that the answer is ‘no’.
No one too major. Not sure who ranks as the most famous:
I know the singers Ahmond and Xavier fairly well. I used to work with keyboardist Jeremy Dean of Nine Days, until the band got signed and went on tour (it was very surreal for me when posters of him started showing up in music stores).
I find that certain authors are casual enough to not mind emailing with or facebook friending people they aren’t strictly friends with (Douglas Rushkoff, Samuel Delaney, Daniel Pinchbeck).
I’m friends with someone who works for Kevin Sorbo, so if I really wanted to I could get in contact with him.
My college physics professor won the nobel prize.
My uncle is author J Sidney Jones, who tends to write a lot of novels set in Vienna.
My cousin was Miss and later Mrs New York State, in the top ten of Miss America, and appeared on the Miss America episode of Fear Factor.
My friend Victor has had the occasional guest spot on various TV shows, and I have another friend who was in a bunch of things as a kid in the UK.
My cousin Nohe is a news anchor in Oregon.
I carried on an e-mail conversation with Terry Pratchett for a while, but that was some time ago.
ExTank, I don’t really have anyone to put here but David Drake is one of my favorite authors.
Dame Elisabeth Murdoch.
My girlfriend has a more active line of communication with him, but I’m sure after reminding him who I was, Richard Herd would remember me.
My friends are friends with lots of famous folks, mostly in the SF/Fantasy and both pen and paper and computer game celebrities. I’m one degree of separation from Mercedes Lackey, Robert Asprin (well… 
), Pam Morrison, Mark Hamill, and John Rhys-Davies, among others.
I knew the marketing director of White Wolf… at least, that’s what she was doing when last I checked. She may have moved on by now.
I have a nodding acquaintance with Richard Garriott, enough that he probably knows I’m one of the people he lets use his theater on a regular basis. I’m definitely familiar to his personal assistant and the people who maintain that site.
I’m good friends with the lady who did the costumes for Space Marines, which you have probably never seen.
Dr. Ian Hancock is one of my former professors. He’s sent letters of recommendation for me. I could email him casually, I suppose.
I’m friends with a few Canadian radio producers, but that’s not really as amazingly awesome as it sounds. 
As far as casually email, though? Nobody super famous.
Closest I can think of is one of the guys from the move The Cove…but he’s not well known, since he was behind the scenes. I’ve met some of the others from the movie, but am not in contact with them.
My father is a longtime friend of Pete Beagle - I’ve had the pleasure of talking to Pete on the phone, and could easily drop him an e-mail. He actually wrote a short story starring my father, and posted an audio reading he did personally. Hugo award winning writer. Writing about his childhood with my Dad. Odd.
My cousin does sports talk in NYC…I suppose he’s famous in the area. He was also a judge on Iron Chef - does that count?
And a girl I went to high school with, and still occasionally chat with on Facebook, is an expert in Mexican drug cartels - she’s been on Fox News…I think CNN…was just interviewed by some Australian TV show. But if you’re not into that scene, you probably wouldn’t have heard of her.
-D/a
Just thought of one.
Will Allen, one of Time Magazines 100 most influential people. Known him since I was a little kid and he was just a poor ol’ corn farmer. Of course I’d be surprised if he had his own email account to begin with.
A couple of higher-ranking diplomats and one completely un-famous jazz sax player. Oh, and the junior Senator from Alaska, Mark Begich.
Errr, I don’t think I could write them casually, but they probably would respond to an academic e-mail or heart-felt ‘how are you doing?’ They’re only famous in their respective fields of New Testament study and Catholic social justice.
Andrew Bogut.
My uncle has been good friends with his dad for about 30 years.
There’s a British woman named Helen Rogers who is a very big name in smooth jazz circles, having sung the vocals on many Paul Hardcastle and Jazzmasters albums, who I’ve developed a bit of an email relationship with and could write casually any time I liked. After wondering about her for years I finally found her on Myspace, where she’d created a site to promote some new music she was doing on her own. She’s basically a studio singer and not an entertainer. She’s very friendly and we’ve emailed back and forth several times over the last five or six years.
But the most all around famous person I could email casually at one time was Steve Wozniak. We spoke several times about a variety of subjects and he even posted some of my comments on his website, which had a section for general purpose letters and another for letters pertaining to the movie Pirates of Silicon Valley. There are certain things that are a matter of character with Wozniak, and personally answering all his emails was one of them. Unfortunately he began to receive a flurry of emails following the broadcast of that movie and it went on for five or six months. He would spend twelve to fourteen hours a day answering emails and it almost destroyed his marriage. I haven’t tried to contact him for several years now but I doubt that he’s still as accessible as he was then. He’s a great guy though and very, very smart.
Pookah falls over
Wow.
You win the thread by miles.
I can’t beat that, of course, but I know various people who are very famous in the field of Irish traditional music, but wouldn’t mean anything to anyone here, I suppose. One of them has recorded with Kate.
Bill Bickel, author of the Comics I Don’t Understand page; I’ve sent him a number of comics submissions over the years.
Some of the people from the early 70’s NYC punk scene.
At least the ones that are still alive…
I still hang with them.
NY Dolls
Planets
etc…
He’s not famous in America, but I occasionally correspond with Australian journalist Jack Waterford, who is a third cousin.