Tons, I’m sure, but I don’t track them. Interesting ones I know I have is a first edition of the hardbound version of 2001, bought seconds after it came out, and a copy of Monstrous Regiment autographed by pTerry. But when I go to A Change of Hobbit I always snicker at how much they want for paperbacks I own which I consider to be junk. The value of my first editions is a problem for my heirs.
Ray Bradbury’s The Illustrated Man (which I got him to sign when I was in middle school).
A.A. Milne’s When We Were Very Young, which I found, quite by accident, in a used book shop in Edinburgh and which I gave my wife for Christmas.
I have a copy of the 1st US printing of A Game of Thrones, purchased back when it was first published, much read and enjoyed.
I also inherited my grandfather’s copy of Godel, Escher, Bach, which might well be from the first printing.
I only have a few, the only noteworthy ones are The Satanic Verses and Deliverance. The guy I bought the latter from joked that it was worth more because it wasn’t autographed.
I own a bookstore, so every time an author comes in with a new book, I have him or her sign me a copy. I have a lot of them. Most are just personal mementos, probably worth less than the cover price on the book, but some have some value to them. I have just a few signed firsts of real significance, like Vonnegut’s Bagombo Snuff Box and Skinner’s Walden Two.
If WWWVY is indeed a first and in dj, you stumbled across something quite valuable. Have you had it looked at?
Truly, this has been the week for coincidences. First there’s the thread about people with no brains, where somebody posts a link about a guy I happened to see on the street a few days earlier, and now here’s a post that mentions somebody I actually know. Is the world shrinking, or does it just seem that way?
Anyway, on topic, I have a number of first editions, the most valuable of which are a bunch of limited editions by André Maurois, some of them signed.
I collect Arkham House first editions. I’m up to about 130 titles. Many are nice books to have but not especially worth anything. Maybe $50 or so. However, I do have some of the rarer titles, such as The Outsider and Others, Beyond the Wall of Sleep, Out of Space and Time, Spells and Philtres, Lost Worlds, Skull-Face and Others, Dark Carnival, and A Hornbook for Witches.
I also have first editions of all of Stephen King’s works. By that I mean the trade hardbacks, not necessarily the signed/limited releases. Most aren’t all that rare, given that it did not take King long to become a publishing machine. But a few are comparitively hard to come by in decent condition, such as Carrie, 'Salem’s Lot, and Night Shift. I do have the Grant firsts of all the Dark Towers, a nice signed/numbered Six Stories, all the Bachman paperback originals, and some of the not as well-known titles such as **My Pretty Pony ** and The Cycle of the Werewolf. I also have a number of first edition anthologies in which one of King’s stories was first published. For example, **Dark Forces ** has the first publication of The Mist. Stuff like that.
Does my 1865 edition of Punch count? (Hard cover but I don’t think there were other versions).
About my Biggles collection…
Per ShadowFacts, my comic collection. Monetarily near worthless (I checked on e-Bay), these are the first and only printings of fine art done by people even crazier than me.
That’s an exaggeration; these creators are usually sane, just in different ways than many of us define sanity. 
AND THEY ARE SO AMAZING AND DIVERSE.
This is starting to be a rant, so I’ll shut up.
I’ve got a few James Bond firsts also: From Russia With Love and The Man With the Golden Gun (both with dust jacket), and Goldfinger (without). And a real curiosity: a first of *Colonel Sun * by “Robert Markham.” Bond-o-philes would know that one as the first non-Fleming Bond novel, and that “Robert Markham” would later be revealed as Kingsley Amis. But of course, there is no indication of that on this edition.
The only one I have is Stephen King’s The Dark Tower: Drawing of the Three, which I came upon quite by accident in a second-hand shop. The owner of the shop had just purchased a large box full of books which he had not cataloged or priced yet and said I could have anything I wanted out of it for $2.00. 
I have a first of Gravity’s Rainbow, which is probably worth something. Also three of the four volumes of Gene Wolfe’s Book of the New Sun. Some others but nothing really notable
Yep - those can go for a pretty penny. Worth looking up on bookfinder.com…
I got Gene to sign the first three volumes when my wife and I had lunch with him and his wife at a con. (How’s that for name dropping? 
) The fourth volume hadn’t come out yet, worse luck.
Yes, he is very nice and a great lunch companion.
Getting autographs are a bit strange when you’re an author. A few people go all out to get autographs from everyone they meet. I’m in the camp of not asking under they are very good friends or authors at the very top of my most admired list, as Wolfe would be. Then it’s as much of a thrill as if would be for any fan.
I have several Agatha Christie first editions.
I got Mr. Wolfe to sign a bunch of paperbacks at a con, but I didn’t get my firsts till later. 
He was a really nice man. I made a little fun of him when someone asked which book of his they should read first and I suggested Jack Vance’s Dying Earth. He laughed and took the joke in good humor and talked to me for a while afterwords. A real class act.
I found vols 2, 3, and 4. I don’t have a first of Shadow of the Torturer.
I play that by ear, depending on the circumstances.
When I meet other authors at conferences, I generally don’t ask, unless they’re at a signing table and I stand in line like everyone else. Sometimes, I’ll swap autographed books with authors–I’ll sign one for them, they sign one for me.
When I meet them in my bookstore, I always have them sign an extra book for me.
I have tons, but the one I value most is the signed, personalized First Edition of Ringworld. You know, the edition with the mistakes in it.
Lots of signed Firsts from Pratchett, Ellison, Niven, Pournelle, Barnes, Robinson, Martin and the like.
Consider me very green, now.