I've seen Ludacris in Costco. I didn't talk to him. He was apparently marketing some sort of alcohol. I also saw Anne Hathaway at a Starbucks. I didn't want to bother her, so I didn't ask for an autograph or anything.
Last but not least, I met George Lucas... he signed my issue of Star Wars #1. He was all right when I met him. This was around the time of a renewed interest in Star Wars when ROTS came out....