The following tools can help make your job of ensuring accessibility easier:
- Fangs - Screen reader emulator that allows you to read how a page would be represented audibly to a screen reader user
- WAVE Toolbar - a browser toolbar that automatically scans for errors on the page
- Link checker - WTS runs a service that can automatically check all your site's links every month and email a report to you
- ConvertDoc - email your image-based PDF documents to email@example.com and it will automatically return an OCR version of the PDF
Additionally, the W3C maintains a list of accessibility tools that you can filter by license and standard.