PDF to accessible format Not without controversy, this site will allow you to upload a PDF and convert it into fairly good HTML or TXT
A break-down of PDF and accessibility This site does a nice job of pointing out the quick-fix and also more accessible process of producing accessible PDFs.
Apple accessibility links Apple maintains a list of useful accessibility links for 3rd party solutions, mac products, community resources, and standards bodies.
WAI-ARIA Overview An overview of WAI-ARIA, the Accessible Rich Internet Applications Suite; a set of documents that lay out how to make Web 2.0 sites and applications more accessible.
Testing Tools
AChecker AChecker is a tool that allows you to type in a url and test for accessibility.
HiSoftware's Cynthia Says Portal This site allows you to type in a url and test for accessiblity, and it also allows you to emulate different browsers while doing the test.