We're talking about getting a trainer that we can put our bikes in to make them stationary bikes - that way we'll get more practice on the bikes we actually use rather than one of those stupid excerbikes that just aren't the same. Something you might want to watch for on Craigslist.
I've always been somewhat intrigued by those. In my case, I only have knobby tires, and I'm not sure how well those would work...but it does seem like it'd be closer to the real thing than the typical exercycle thingie.
Don't know that I've ever seen 'em on Craigslist, though...maybe because the folks that have 'em use 'em.
http://www.cycle-ops.com/p-115-mag.aspx
So...such things actualy exist. I suppose they have gadgets you can tighten to make them resist more.