Creative Artists Agency
9830 Wilshire Blvd.
Beverly Hills, CA 90212
I have never written to CAA (the agency which represents him), but I'm sure that Al does not personally respond to letters. If you sent fan mail you would probably receive only a photocopied autograph and letter, although don't hold me to that.
Chal Productions
75 Rockefeller Plaza, Suite 1804
New York, NY 10019
I haven't written here either. Chal is Al's own production company. If this address is legit, Al might get the letter, however his desire to respond might be shaky.
301 West 57th St. Apt. 16C
New York, NY 10019
I have written here, but I did not receive a response (although I did not know the apartment number and am still not sure if this is the correct one). On a recent trip to NYC, I visited this building, which is a very nice set of apartments. I asked the doorman if Al still had an apartment there, which is what most people thought, but it turns out to be his office. This might be a good bet to write to.