I collect Frank Herbert books. My favorite is an autographed Dune Messiah paperback–it’s beat to hell and not in any condition of worth, but it’s clearly been well-read and loved.
My oddball piece is the “Dune Movie” pop-up book. It came out prior to the actual film, so the art in the book doesn’t look anything like the end-result actors or props from the film.
I collect the National Geographic magazine, and the maps that would be inside them. I have at least 1100 issues. It’s getting harder to collect now, because the ones I don’t have are so far back(pre-1914) that they’re getting expensive. I paid $50 for a map from 1896, the only 19th century piece I own. Someday I’d like to own one 19th century issue.
Where do I start. I have a number of collections.
Probably the one I’m most proud of is my Crayola Crayon collection. Most folks know about the basic 120 or so colors available today and some of the retired or those that had their named changed. With all the custom color names of crayons made by Crayola, there is 712 unique color names, I have about 550 of them. I have a couple of favorites. One is a box of 8 crayons in mint condition from 1922. The other is a box of 4 crayons made for Canadian IHOP restaurants in the early 1990’s. They are probably the rarest set of crayons made by Crayola, a mint set would set someone back about $300 today. Yep, that’s $75 per crayon.
I have over 500 Monopoly tokens. I have virtually all the standards most folks know about, this includes the original wood tokens from 1934, the paper and chalk tokens from World War II and the gold plated tokens from the Franklin Mint set. Then add the tokens from all the other versions of Monopoly I have, the complete set from Johnny Lightning and some rare custom tokens made by a fellow collector in Pennsylvania. My favorites are an original lantern with the glass insert from a 1935 set and a sad face custom made pedal car token which leads me to number…
A few years ago while doing a search of Crayola on eBay I found someone selling Crayola branded diecast pedal cars. I bought them and that started a new collection. I now have about 40 different diecast pedal cars. Then things got a bit out of have for a bit, I bought a couple full sized pedal cars. One is an original 56 Plymouth from Radio Flyer and an early 80’s John Deere tractor with trailer.
Skunks. I have a bunch of skunks. Everything from a small one carved in Japan from a tiger tooth to a stuffed one over 5 feet long.
NASCAR diecast. I no longer actively collect them anymore, I have over 3000 of them and no room to store or display them. The manfacturers have flooded the market the past few years making my collection worth very little. Most are current in storage.
I also have some collections that I consider myself a casual collector, if I find something for a reasonable price I will buy it but I don’t search for the items. The collections are 50’s and 60’s 1/64 scale diecast American cars, various knives including fixed blade and pocket knives, cribbage boards, soda bottle salt and pepper shakers and retro art posters.
I collect U.S. travel ephemera. The first thing that comes to mind is a postcard mailed from Zion National Park in 1938.
Books in general. SF short story collections from the late 50’s to mid 70’s more particularly.
Automatic Timex watches from the 60’s and 70’s.
I collect versions of Moby-Dick by different illustrators. There are hundreds. Rockwell Kent’s version is probably most celebrated, but I like Boardman Robinson’s personally. And Sam Ita’s pop-up book is really terrific.
Oh wow, that sounds absolutely, totally cool! You have *got *to put a photo of it up on Photobucket or something. Maybe a nice 1024x768 picture I could use as a background on my pc. 
I collect Brian Froud signed prints (2) and his books. I have a first edition Fairies that has a tiny bit of foxing on the dust jacket. I hope to get it signed one day. But my favorite book is a copy of The Goblin Companion which was bound upside down. And Jesa McBeth has signed one my Fairie Oracle cards.
I also collect hand made roses.