This has been contributed by Girish Managoli, an employee of MindTree.
There are a large number of web users with different needs. How do these people access information? How do they read? What do they actually see? Do they find the web friendly?
There are many types of users with varying needs:
The Visually Impaired: This group typically uses a screen reader (like JAWS) or a screen magnifier (like ZoomText). Pretty layouts, color coordination, nice looking fonts- none of this matters. They look for ways to quickly get to the content not having to wade through a lot of junk. Drop-down menus, pictures without ALT text and not knowing what a link does before clicking are some of their peeves. This group does not use the mouse. They rely on voice inputs. Any website or application that relies completely on the use of a mouse is out of bounds for this group.
The Deaf: This group has no use for sounds and relies extensively on visual content. Non-captioned videos are their pet peeves.
The Dyslexic: Controls that cannot be accessed easily, cluttered links and small fonts put this group off. They would like to have their content organized and the flow predictable.
Other Impairments: This group includes users with motor and neural impairments like cerebral palsy and multiple sclerosis. Like the dyslexic, this group would like to see their content uncluttered, avoiding unintentional clicks on surrounding links. They would want to quickly access information without having to click or scroll multiple times.
Apart from the above mentioned groups, there are others users like the color blind and the users with multiple disabilities like deaf-blind.
Accessibility is important for all of the above. The web is extremely powerful and has changed lives like never before. It brings them information otherwise inaccessible and enables them to be more aware of the world. It has made them find new interests from around the world. It has made them independent; allowed them to find new vocations and has made a whole new life possible.
Now, it only makes sense to make the web more inclusive.
Software Solutions To Accessibility
I recently stumbled upon an action program that promotes accessibility. It’s called "Scripting Enabled". 
The event dedicates the first day to listen to the problems faced by users. The second day is aptly called "Hack Day" where real developers get together to create real working prototypes that solve these problems.
Samples From Hack Day:
The Visually Impaired
The problem: For the visually impaired, Slideshare is difficult to use to find the text. Here’s an example: http://www.slideshare.net/AfshanKirmani/an-introduction-to-graphic-design-presentation
The solution: Easy Slideshare (shown in Figure 1), a hack that extracts and displays only the text from the slides.  The figure below shows you the content from the presentation where the tool was able to extract this information.
Figure 1: The Easy Slideshare tool that displays the text of a presentation.
The Dyslexic And The Physically Impaired
The Problem: The controls of YouTube player are small and difficult to access.
1. The Easy YouTube (shown in Figure 2), a hack that displays the video with large controls. 
Figure 2: YouTube vs. the Easy YouTube, a hack that displays the video with large controls.
2. YouTube does not make it easy to add captions for videos. Another hack, the YouTube captioner (shown in Figure 3), provides you with the possibilities. 
Figure 3: The YouTube Captioner allows you to add captions.
Tips From Developers:
• Searchability of Flash 
How important is accessibility in the context of our day-to-day lives? Is it relevant to us as something more than an academic interest? I would love to hear from you.
Please leave a comment or email me at Girish_Managoli [at] mindtree.com
 First presentation on http://scriptingenabled.org/presentations/
 &  Presentations and links on http://scriptingenabled.org/presentations/