There’s a fairly active community of people doing wet-plate collodion photography. See, for example, Robert Szabo’s website for lots of examples of this photographic process. What I personally find somewhat disappointing is that so many photographers try to re-produce or re-create photos taken about one hundred years ago - why anyone would want to re-create photos from the grisly US Civil War completely escapes me. And don’t even get me started on those people who dress up to re-stage it (do people learn anything from historical disasters?). I think it would be way more interesting to take photos of contemporary subject matters using these techniques.
(thanks, Mark!)

Update (7 July 2004): Quinn Jacobson emailed me to tell me about his own collodion photography. Make sure to check these photos out!