Speaking of paper aeroplanes... have you checked out stuff here (sites are mostly Japanese-language) [Okay, these might not be adaptable for use as parasite gliders for model rocket, but then they're certainly likely to be fun to put together and fly] ?

"profile" type (i.e. fuselage is flat piece)
http://www.infosnow.ne.jp/~suzuki-a/
http://homepage3.nifty.com/papercraft/ (click on the red box)
http://www.amy.hi-ho.ne.jp/h-nishimoto/index.html (click on pcraft link)
http://www10.ocn.ne.jp/~papiy/home.html (click on "Paper gliders" link)
http://staticwind.soragoto.net/index.html (click on "gallery")

fuselage is 3-D style
http://ojimak.web.fc2.com/index.html (note: some models like the Osprey don't fly)
http://www2u.biglobe.ne.jp/~poseidon/e_index.html