In an ideal world, it seems to me like everyone needs a different interface with a computer, whether it's a website or an application (remember those?).
Waving a wand, I'd take something like a banking website (let's say Bank of America as an example) and strip out all the cruft. A text-only interface that (maybe) just looks like a simple early-version-of-Windows application. I'll grant that Amazon and eBay require the ability to put up images, Vanguard and Fidelity most certainly do not.
What you could do then is to make them all alike, it's not like these sites are particularly different. Maybe the equivalent of an RSS feed app could run the lot.
The thing is, a deaf or blind person could ask for the same thing just with their own particular abilities in mind.
/oldmanrant