first off... the best of all, is Space Station 42. here is link:
http://www.ss42.com/toys.html
then click on category you are interested in. lots of links are in there. all free of course!
Some of these links are famous and maybe already found out, but just to be sure...
Currell models, very interesting.
http://www.currell.net/models/mod_free.htm
Papercraft World, if you're interested in most non-vehicle things
http://papercraft-world.blogspot.com/
Stalhart Papercraft, a bit aircraft with TONS of versions per model
http://www.hoxity.de/papercraft/
http://www.ss42.com/toys.html
then click on category you are interested in. lots of links are in there. all free of course!
Some of these links are famous and maybe already found out, but just to be sure...
Currell models, very interesting.
http://www.currell.net/models/mod_free.htm
Papercraft World, if you're interested in most non-vehicle things
http://papercraft-world.blogspot.com/
Stalhart Papercraft, a bit aircraft with TONS of versions per model
http://www.hoxity.de/papercraft/