I like apsfilter, works instantly for my "killer" canon bjc-4100 because ghostscript supports it. You are pretty much limited by what ghostscript supports.
-- Windows NT: n. 32-bit extensions and a graphical shell for a 16-bit patch to an 8-bit operating system originally coded for a 4-bit microprocessor, written by a 2-bit company that can't stand for 1 bit of competition.