How to get this effect?

I've been trying to search for tutorials on how to get this kind of sketch effect (if it's even called that) but could not find any good ones. As you can see the renders in this graphic look as if they're sketched and has this vintage look to it. Anyone have an idea to get this effect? Much appreciated.

http://fc04.deviantart.net/fs71/i/20...rs-d32cebv.png

EDIT:
Sorry if I'm not being too specific. Here's another example, it looks like the render has this sketchy/paint effect? I think it's filter?
http://fc01.deviantart.net/fs51/f/20...miroKnight.png

i see no special effect o-o

maybe the hat is like that? D:
if its not like that then he used a texture.

topaz plugin

http://brushesps.files.wordpress.com/2010/03/topaz5.jpg

Got it, thanks Ishamz!

i dont see topaz in the pic but ok o.o

with topaz you can make things grungier too, its not just making it smooth lol