I met the crown prince Hans Adam Liechenstein at a conference on UFOs in White Sulfur Springs West Virginia at the Greenbriar Hotel. He was very understated and I did not discover who he was until after luch. Shortly therafter he became the ruler of Liechenstein. I send him a letter, to which he replied in a friendly way.
I’ve seen King Juan Carlos and Queen Sofia of Spain (from a distance, across a VERY crowded plaza, and I’m not even sure which ones they were). Not quite as impressive as yours, I’m afraid.
I’ve also been photographed on the same roll of film as Queen Elizabeth, if that counts for anything.
I haven’t met him, but apparently there is a student where I work who is a Prince of a nation that no longer has a monarchy.
I didn’t go, but Queen Rania of Jordan recently spoke at my college’s graduation. (Of course, I graduated the previous semester…)
I attended a Church of England service in St. James’s Palace and sat across from the late Queen Mum.
When I was a few months old, I apparently met the late Princess Diana when she came to Victoria, Australia in the early 80’s. Of course I don’t remember it. Dang.
I’ve seen king Carl Gustav of Sweden and his grandfather king Gustav Adolf.
Once in London I saw the queen mum putting down flowers at some monument (but I was so far away I could hardly make her out).
I saw Queen Elizabeth and Prince Phillip in Ottawa in 1981, they were there for the repatriation of Canada’s constitution. They walked about ten feet away from me and I made Prince Phillip laugh (a dubious accomplishment considering what we know about his sense of humour these days) by shouting God Save the Queen… and Prince Phillip too!!! At the same occasion my best friend in High School got to attend a royal dinner.
Keith
From the dorms at Westminster where i stayed two summers ago, we watched the princes and Queen Mum frolick at outside banquets in beautiful gardens drinking wine and socializing. The older Prince (forgot his name :o) waved to us as the president of the student body tried to organize the rest of use to do a “sic’em bears” thing (raise your hand like a bear claw and unbend your elbow 45 degrees, then return it to it original position----it how we cheered at the football games for Baylor). I hope he felt really silly.
My father is pretty good friends with Prince Albert (from Monaco, not ‘in a can’). I’ve met him a few times, he is nice and down to earth.
I haven’t met any reigning monarchs, but on the other hand I have met a whole lot of queens! 
I had lunch with the Duchess of York a year or two ago, when she started shilling for Wedgwood. I pretty much ignored her and chatted with Lord Wedgwood, who lives in my hometown (Phliadelphia) and was utterly charming. Fergie was nice, too, but I was really more interested in what he had to say.
Oh—and I had a brief correspondence with Prince Charles about architecture. He gave a speech on preserving ancient buildings and decrying much modern architecture which struck a cord with me. So I sent him a note, and he sent me a very nice reply.
Nice fellow . . . I hear he’s single again . . . Hmmm—“Queen Eve” . . .
Well I shook Nelson Mandela’s hand one time which should count for SOMETHING.
Also I spent an evening arguing race relations at a party with this black dude who I later found out is a Zulu Prince (we were both so drunk I cant even remember what he looked like!)
Met face to face: Prince Philip, Prince Andrew
Seen at close quarters, just a few feet away: Prince Charles, Princess Di (separate cocasions)
Seen in real life but only as part of a passing crowd: Queen
Two of these (Phil and Chuck) I’ve actually shot.
The Queen Mum, from a long way away, about 12 years ago in Winchester.
Juan Carlos spoke at my brother’s graduation ceremony in the early '80’s.
I attended a private tea for about 40 people with Queen Liz. There was tonnes of heavily armed security surrounding the garden patio the tea was held on - interesting ambiance going on. I have a photograph of the Queen and me chatting and shaking hands.
If I recall, we wern’t chating nearly as intimatly as the photo suggests.
I saw the whole UK family at the Remembrance Day ceremony at the Cenotaph back in 88 or 89. In 1990 I met Princess Di when she visited the British Deaf Assosicate conference (she gave a signed speach too). I was in the children’s group room and she came in a chatted to me and my friend Michael about how we liked it there and were we having fun. Mostly I remember that she had a blue twin-suit on and there was lots of press photographers.
Later that day a little girl I knew who was supposed to be presenting her with flowers gave her the flowers and then promptly lifted up her skirt and announced “Look! No nappies!”. Princess Di chuckled.
Above-mentioned friend Michael’s step-mother was the person to whom the ever-tactful Prince Phillip made the “No wonder you’re deaf if you stand so close to all this loud music!” remark.
I lived in the same dorm as Prince Frederick of Denmark while he was studying at Harvard.
I don’t know if this counts as royalty, but I was also classmates with the daughter of the Aga Khan.
I was studying history in London during Charles and Diana’s wedding and saw all the attendees from streetside near the church. When Diana looked over and saw me, she touched herself inappropriately.