@earsup I am very jealous, I'd love to meet Madonna!
For the PP wanting context -
Debbie Harry, Chris Stein and Clem Burke all signed a CD booklet for me, the only one who got a photo with me was Chris, he put his arm around me and his wife and little girl were playing on the grass behind us. Debbie didn't want photos with anyone, she didn't have her make up on yet (but she looked good without it!), she was drinking a cup of tea and smiled at me after signing my booklet 
Quentin Tarantino was signing copies of his script/book for Death Proof, he shook my hand after signing and said 'sorry sweetheart, no photos' but my ex sneakily took a photo of us, it's side profile but you can see him clearly 
Juliette Lewis was signing copies of a CD but we hadn't bought it, we hung around in HMV until she was done signing all the CDs and my ex asked politely if we could get a photo, she took one of us and Juliette had her arm around me and it's a lovely photo, she was so nice to meet, very very friendly
Dawn French and Jennifer Saunders were leaving after we went to their show around 2007 - they signed some DVD inlay things and each got a photo with me and then Dawn French said 'right missus, you ready to go?' to Jennifer and they went off in a black car. Both were friendly but tired after their show.
Sharleen Spiteri signed a CD booklet for me and got a photo with me, she was lovely, really chatty asked if we liked the new album and if we were going to the show later 'yes!' and it was awesome - that was 2005/06. I was a huge fan of hers growing up
Bret Hart was doing a book signing in Edinburgh, I loved watching him wrestling in WWF/WWE when I was 9 years old, met him when I was 25! I couldn't stop grinning the whole day, my face hurt so bad afterwards, lol, he was lovely, signed my book and got a photo with me, he was so tall and muscular, I couldn't reach his shoulder so I put my hand on his back I look tiny next to him, haha!
Hugh Cornwell was doing a book signing but we hadn't bought it, he came over to say hi and briefly chatted, I mentioned Joe Strummer (who had died about 4 years prior) and he said 'oh yes' and looked sort of wistful.
David Suchet, omg! He was SO nice! Very friendly and chatty and he smelt amazing, I should've asked what aftershave he had on, whatever it was was beautiful! He signed a Poirot booklet from the DVD box set we had We had gone to see him and Laurie Metcalf in 'A Long Day's Journey into Night' (it was good) and waited outside at stage doors afterwards. Then we saw Laurie and she signed my Roseanne DVD box set, she looked pleasantly surprised that I brought it, she was very nice and quite shy. Both got photos with me I wrote them both thank you cards and sent them to London afterwards where their next show was.
Billy Idol, although not sure it counts, but when he was on stage he took my CD Booklet and signed it and passed it back through the crowd to me. He threw out signed paper plates too and we caught one He was bloody brilliant live. I wish he would tour the UK again.
Almost met Siouxsie Sioux but she didn't stop, she looked a bit stressed and unapproachable so we didn't go over to her. She was carrying a bundle of bottles of water.
Saw Karen Dunbar in a ladies loo queue but again she looked pissed off so we didn't try to talk to her, lol.
My ex saw Alan Carr coming into Borders to sign books but he was pissed off and complaining, lol! She didn't go over to him, hadn't anything to sign anyway.