Was thinking about an old tool I made called CodeBlind, back in 2003. It was a rather ugly tool - made when I was experimenting with building skinned apps, but had a fair number of features like simulating various types and severities of color blindness.
Here's a screenshot of using it while I type this, with both the filter/magnifier and options up.
Been debating about updating it, adding camera support, porting it to all the platforms I can, and generally making it release worthy - but I only want to do that if people might use it.
Here's the old tool if anyone is interested - please be gentle, it really is old and I never finished it :) Note that the domain (codevis.com) is long since dead and the email in the program is no longer valid.
If something similar would be useful for anyone, let me know. And tell me what it'd need that the current tools don't already provide!