Here are a some tools tools and resources that you can use to check your site while in development and after it's complete.
- Cynthia Says - The HiSoftware Cynthia Says portal is a web content accessibility validation solution. It is designed to identify errors in your content related to Section 508 standards and/or the WCAG guidelines.
- WAVE - WAVE is a free web accessibility evaluation tool provided by WebAIM. It is used to aid humans in the web accessibility evaluation process. Rather than providing a complex technical report, WAVE shows the original web page with embedded icons and indicators that reveal the accessibility of that page.