- Google Search: Sometimes, all it takes is a quick Google search to find a paper. For instance, say I'm looking for Marsh's old paper on characters of Odontornithes. I type "Characters of the Odontornithes, with notice of a new allied genus" into the old Google search box, and what do you know? It gives me a link to Matt Wedel's archive of O.C. Marsh papers! Sometimes, of course, you might have to try a few variants on a search before you hit on the right PDF. Often, when I'm doing initial research on a topic, I'll type in "[taxon or topic name here] pdf". You never know what you might find! For instance, typing "Triceratops PDF" gave me a link to several very relevant papers. Google Scholar also works pretty well in this regard (and will often filter out most of the non-scholarly stuff).
- Google Books: I have had some real success, particularly with older works, on this search engine. I strongly recommend setting the search settings to only find books with "full view," if you're not interested in just snippets of text. Once the recent settlement with publishers gets worked out, I think we can expect some really good things in terms of low-cost access to out-of-print but in-copyright publications.
- Scribd: This website offers browsable documents for a surprising number of paleontological papers, although you must be a registered user (free) to download PDFs.
- Journal Archives: Many museum publications, such as Fieldiana and all of the AMNH publications, are available online. It's always worth checking out museum web pages to see if their old publications are out there. A number of journals also have freely available archives. 'Nuff said.
- Author's Web Page: More and more scientists have PDFs of their papers on their web page - so, it's always worth a quick search to see what's available.
- Writing the Author: If you can't find the PDF for a recently published article through other means, send an email to the author. As I mentioned in a previous post, it's a great ego boost for those of us who write scientific papers!
Disclaimer: It is entirely up to the user to be aware of any copyright restrictions that may apply to the download or use of any of the resources addressed here.
Update: Dave Hone has posted a really nice continuation of this theme over at his blog.