One example was when we played through 2E Hour of the Knife. I had this minature grandfather alarm clock. I thought it was the cheesiest thing...then I decided to try and incorporate into the game. I would set it to 11:00pm, and give the PCs one hour to catch the killer. We played that hour in "real time." (kind of like the show 24) The players would get real antsy as the clock ticked down. It also meant that if the players started goofing off, they'd lose time, and face consequences.
Another time, I was getting ready to have my PCs go through When Black Roses Bloom. But that wasn't until later in the campaign. Currently everyone was in Nova Vassa wrapped up in a Nightmare Court campaign. One of the PCs was a Dementlieuese nobleman and a friend of Tristen Hiergaard. When Tristen invited them over to his castle, the PC entered his study and found a book entitled "Knight of the Black Rose."
Tristen told him to keep the book as it gave him the chills. (In gameplay, no one seemed to know who actually wrote this book.)
So I took out a real copy of the same published book and gave it to my Player. My player read the book in real life and we assumed his PC was doing the same thing in his spare time behind the scenes. When the player was done, he passed it onto two other players from the group. Two of them were diehard Dragonlance fans and were exicted to hear a story about Lord Soth. Later in the campaign, they were forced to enter Sithicus (for their own reasons). The PCs (and the players) learned that the book given to them by Tristen was NOT fiction afterall. Lord Soth and all the other characters were alive and kicking in this strange land. This was what lead them to get involved in the adventure WBRB...
Anyway, does anyone else use props as techniques or devices for their adventures? I'd be curious to hear some fresh ideas.
Probably the fanciest (and most fanciful) prop from that campaign was a small grimoire he did up himself. If I can find it in this apartment, perhaps I can get some photos of it...
The ones I make most use of are maps. So much so that the first thing my players do in a new town is look for a scribe or mapmaker.
I've also used them for puzzles extensively. There have been gears to decrypt the mad clockmaker's journal, and a strange puzzle-box contraption with numbers that I actually built out of foamboard.
I love aging notes, letters, and other writings with tea and the like. (note, don't use soy sauce. It looks great, but smells like soy sauce forever.) One time I sealed a note with wax. That was fun. Gives things that authentic feel.
-Eric Gorman