I was at the Higher Ed Web Dev conference last week, and Jim Brandt mentioned in a talk that they could use a module to check various accessibility things (such as Section 508 or Web Accessibility Initiative).
I volunteered right then and there to get one started, and so I did. It's Test::WWW::Accessibility.
The problem with this sort of thing is that so many things are subjective. A perl test script won't be able to determine if a color conveys information or is just pretty, or many of the other things Bobby likes to caution against.
There are things that we can check, though, and if anyone wants to help me add them to the module, just send me patches.