Accessibility guidelines and support documents from Pearson. The guidelines are based on Section 508 and WCAG 2.0. The training and training materials aren't openly available, but the guidelines and templates for accessibility reviews are.
Link & Learn Taxes, linking volunteers to quality e-learning
Example of (theoretically) accessible e-learning Section 508 created for the IRS. Publicly available. Lots of little errors though; spaces in alt tags, paragraph tags with formatting instead of header styles, etc. Given as an example in a discussion in a LinkedIn group.