There has been a lot of discussion about making web sites accessible for people with disabilities. In the UK it is a legal obligation for companies to not discriminate against disabled people, intentionally or otherwise. There is a recent article on A List Apart discussing UK legislation, and it's implication on web designers.
In the US there are similar obligations on companies receiving Federal or state funding, and on government agencies. Most other countries have, or are about to have, similar legal obligations.
In the UK, the Disability Rights Commission undertook a survey of major UK companies' web site, and found that most failed to even meet the most basic accessibility standards. Though you can split hairs as to what is and what is not accessible, it's clear that most sites are not on the whole accessible.
We are about to launch a redesign site at work, and it's clear that our legal advisers are oblivious of the law, as is our graphic artist/web designer. In conversation with a colleague he was quite dismissive of the disability issue, not because it's not a valid point, but rather that most web sites have such awful usability/accessibility for "normal" people, that the disabled issue is really a small part of a much larger problem.