I have a couple of old Speed Graphics. I really want an Aero Ektar lens, but mainly because of the cachet, so I probably won't actually get one. The nice thing about the Speed Graphic is it's infinitely configurable and CHEAP. You can mount up pretty much any lens regardless of whether it has a shutter or even an aperture, and just use the back shutter to control your work. You can take pictures on almost any film, including X-ray film and printing paper, if you can shove it into the film holder or Grafmatic film changer. It's kind of a bit too much room for creativity, at least for me, so I often can't cope and just *don't* take pictures. Which is admittedly silly.
I've been taking photos with it on the peel-apart Polaroid 669, of which I found a nice cache in a biology lab that was closing down and had used it for cell imaging back in prehistory. It was very nicely expired and creates some neat effects. Also luckily found the Polaroid back, with the rollers for processing the film and all that stuff. The neat thing about Polaroid 669 is that you can blot the part you normally throw away, on a hot plate with some watercolor paper, and get even more neat effects.
I also have about a hundred of those old magnesium flashbulbs that someone gave me for free, but no idea what to do with them besides play practical jokes by putting them in friends' car dome lights and such. I need to find a cave to photograph the inside of.