"Close your eyes" isn't the answer I'm looking for, but +1 to you if it was your first thought.
I'm putting together an awareness campaign called Browse Blind. The goals are to:
Help sighted people experience the Web as a visually impaired user for one day or more.
Show video footage of visually impaired users browsing popular sites such as Facebook.
Encourage webmasters to take a more active interest in making their sites accessible.
Demonstrate the features that make a site accessible, and those that impede accessibility.
Make the Web a better place.
The project came about after a health scare that resulted in three trips to a local eye hospital. My sight is OK now, but it struck me that, as much as web designers and developers wax lyrical about accessibility, very few seem to have used a screen reader for any length of time (myself included) or considered what their online experience would be like if they suddenly lost their sight. And not a single one of the 100 or so webmasters I've spoken to about accessibility have watched partially sighted users browse the Web. (It's one of the topics I always bring up at Web conferences.)
My questions are:
What is the most common method of Web access (and the name of any related software) for partially sighted users?
How can I simulate this method so that a non-technical sighted user on any desktop platform can browse the Web in the same way as a partially sighted person with minimal setup steps?
For question 2, I'd like to avoid recommending that people download and install a screen reader for their OS if I can, because I think doing so will drastically reduce the number of participants. So I'm looking for Web based simulators (and browser plugins if they exist).
If you know of a cross-platform screen reader that's easy to set up, then that might be an option too, as would step-by-step guides that turn a Mac or Windows OS and browser into 'accessible mode' without further software, as long as you're sure that this is a method that partially sighted computer users employ.
The closest in-browser screen reader emulator I've found so far is WebAnywhere. (Warning: audio plays as soon as you click that link.) It's technically very impressive, but it's a beta, and it doesn't yet appear to work reliably as a functional web browser. If there's nothing out there like this, that's fine as an answer too. (I'm prepared to build something that emulates the most common access methods, but I need to understand what those are first.)