OK. Where do I even start?
How about TechMatrix.org?
If you've never been to TechMatrix.org, ya gotta go there. Whenever I've trained AT teams about Assessment, and we've walked through the SETT framework, and the team members just don't know what tools are available to fit the features that their students need.
On TechMatrix, you can search for AT, Reading, Writing, and Math tools. AND, you can generate a matrix of tools by feature. When you've generated your matrix, you will see your list of tools that offer those features across the top and a list of features on the left side.
If you click on the name of the tool at the top of the page, it will take you to another webpage that will give you additional information about the tool (webpage, price range, etc.) It will also give you a tab that lists features, and a third tab that lists...
And the amazing thing is that the research is based on the features that the tool offers, not the tool itself.
I've tried to upload a Jing screencast of this tool and am currently wrestling with the size. I'll post it as soon as I win ;)