Been a while...
I've been working on a presentation for my technology in the classroom course and have simply immersed myself in the W3C accessibility issues out there.
Much like you, I simply didn't think about it. My initial reaction to having been left with this topic is: they make computers for the blind? How? Why? Insensitive? Maybe.
For the most part, in our daily Torontonian lives, we do what we can and have laws in place to help out those differently abled. Wheel chair access, preferential seating and parking, elevators, bathroom facilities, etc., we do our part. But when it comes to computers and online practice, it is very clear that we aren't dong enough.
Take for example the elderly. With an increasing aging population, we are going to have a considerable amount of people that do not use computers regularly, yet they will be required to use them more as they get older. Design and use must be fully integrated so that this generation of people will have the ability to contribute to our ever-progressive society.
For those people with challenges in vision and hearing, how can websites be made that allows them full functionality? For those of living without these issues, we probably do not give it a thought. It simply does not affect us, but it may and probably does affect someone we know.
wave.webaim.org is a site that scans a page and lets you know of any issues that a person may have. Obviously, everyone should aim for the coveted "no issues" (as did yorku.ca; June 5, 2011), however, anything less than 10 shows that very little needs to be done to get to full accessibility.
Places to start:
W3.org The hub of accessibility guidelines
Accessibility Theme Song A fun video that shows the necessity of being Accessible; also the only time someone will rap WCAG
Mario Addesa Blog The TCDSB guru for accessibility; Mario has been working for years in the Special Education Department and now has this resource filled site for educators.
And there's more, but you can find them all, as did I.