I use my finger nails on the downstroke, sort of raking it along the strings. Only when I'm doing big, distorted power chords, but it saves me trying to grab a pick and means I can enjoy making massive amounts of filthy noise. Which is nice.
Closer inspection reveals noticeable wear on the nail, but I've been doing it for years, and it's never been a problem. I catch all kinds of hell when I go for a manicure though...