Oh. my. god. I just realised, after about 10 years of wanting to make my own shirts but thinking it logistically impossible, that after using photo emulsion on a silk screen you can still re-use the screen! I bought a screen years ago and only used it once, having found the process of cutting out letters from litho paper with a Stanley knife to be waaaaaay too annoying. Holy crap, this makes for interesting proceedings! I see in my future self-made tshirts… Many self-made tshirts…! :D

A video of the whole process: http://www.videojug.com/film/how-to-screen-print-t-shirts
The scungey Instructables way (good for reading the comments at least): http://www.instructables.com/id/Screen-Printing:-Cheap,-Dirty,-and-At-Home/
Coating the screen with photo emulsion fluid: http://www.ehow.com/how_10854_coat-silk-screen.html
Removing the photo emulsion fluid: http://www.ehow.com/how_10852_remove-photo-emulsion.html