You can use the inbuilt Cel renderer - see pages550-556 in your manual -
oherwise there is the Wireframe plugin from Paul Everett,if you want a shader -
http://www.tools4d.com ( check out Mesh surgery while you are there...)
or the 12 point0 Cartoon Renderer plugin from Jörn Loviscach at
http://www.l7h.cn/cgi-bin/index.php?a=3
or the WFRrender plugin from Nekoyama
http://homepage3.nifty.com/nekoyama/plugin/pluginindex.html
or Wire, from Mang-Ky
http://homepage.sunrise.ch/mysunrise/jane_meyer/index.html-
They all have pros and cons- shader vs. rendering effect...
and if you want to acheive really professional Cel rendering quality, check out the soon to be released SKETCH And TOON renderer from maxon (
http://www.maxon.net) -it looks Really impressive .-
jp