While I enjoy paper modelling for its own sake, most of the time it serves as an adjunct to my other hobby, historical wargaming. I am just finishing up a series of 1:900 scale mid-eighteenth century ship models, intended to be used to recreate the naval battles of that era. The scale was chosen as a compromise between keeping the parts from being too small to handle (since most wargamers are relative newbies to card modelling), and keeping the models from being so large that they hog up the available gaming space. They are also fairly simple kits (only a half dozen parts) since the build will have to be repeated several times to make a useable fleet.
This series is closer to a pure card model (unlike my previous ones which used balsa as hull forms), using wire and thread for the yards and rigging only; the hull and sails are entirely from paper.
I have posted a free sample model to my site:
War Artisan's Workshop - 1:900 scale ships