Where to get pulp - free stuff

For public domain stuff, you can try Project Gutenberg and its Australian counterpart, though you need to know what author you're looking for.

Likewise with Librivox, which is basically the audio version of Gutenberg.

Pulpgen has an excellent collection, although the search interface isn't the best.  All files are in pdf.

Munsey's is another good place, though not as updated as it used to be.  There's a wide variety of formats for each story.

There are a lot of good collections on Mobileread - do a search under "omnibus".