Living in southern California, I get the opportunity to see well known folks from time to time.  In all honesty, I don't pay them much attention....  
I did, on one occasion, hold the door open at a Starbucks for Kathy Ireland.  I was going in for a cup early in the morning up in Santa Barbara and she walked up behind me.  I held the door open before even looking back.  As she passed, she kindly thanked me.  When I got in line behind her, she offered to let me ahead of her in line since I had held the door.  I did not recognize her at first, because she was in sweats and no make-up.  I just thought she was a pretty girl... 

    I let her stay ahead of me and heard people whispering about who she was.  Once I got my coffee and was leaving, she was walking out in front of me and held the door open for me....lol  Not much of a story...
On another occasion, I saw Jamie Lee Curtis shopping for furniture in downtown Santa Barbara.  Did not talk to her.  I have always liked her, but I am just not one to bother folks.
I did get the opportunity to hold a short conversation with Don Rickles on a flight to Vegas once.  I was reading a book and he sat down in the seat across from me.  He commented on the book (he had read it too).  We talked for 4-5 minutes and I told him that I had always enjoyed his comedy.  He said "thanks" and that was about the end of it....
I have had several other opportunities, and have actually worked on some custom homes for a few.  Being one to enjoy my own privacy, I have a tendency to just ignore my surroundings.  My wife laughs at me, but I figure they are not any better than the rest of us.  I truly admire some of them, and envy their talents, but don't really get all that excited....  Plus, I am not a great conversationalist and would never know what to say if I did want to meet someone.... :unsure: