DIY solder mask + toner transfer
A technique for applying solder mask is described here:

http://retromaster.wordpress.com/pcb-making/

You should join the Homebrew PCB group, this sort of thing gets discussed there all the time:

http://tech.groups.yahoo.com/group/Homebrew_PCBs/

I found the technique mentioned above by searching their messages. Techniques for applying silk screen come up frequently, as well.

I use the photo-etch technique, which makes things like solder mask and silk screen much easier than with toner transfer. I don't bother with them, though.