There's an active community of people in the demoscene writing code for long-"obsolete" platforms like C64, Atari, NES, etc. These platforms are slow, quirky, and relatively limited, yet they can do all these amazing things with them.
Seeing all these HTML5 "new features" demos, the thought occurred to me: what can we do with a more limited browser? Not something really limited like Lynx, but something still considered obsolete yet maybe more powerful than most people would think. How about IE6? It has JavaScript so you can write programs in it, lots of undocumented/buggy behaviour, and relatively slow, so could be compared to a C64 in some ways. (Lynx would be like a 4004.) What sort of things can you do with it? Should there be a demoscene category "Platform: IE6"?
The issue with Cudder is that he only browses /prog/ and some text-only GNU pages. That's why any browser that can do slightly more than that is considered useless and cancerous.
Wrong on both my web usage and gender. The Internet is much more than stupid Web 2.0 sites filled with flashy mind-numbing uninformative content. If not using a browser with those latest features means I miss out on that, then so be it --- I don't want to see that shit anyway. (Have you seen Imageshack's page with and without JS enabled? The latter is usable, the former is bloody obnoxious with its popup divs, hiding image links, "social media" crap and whatnot.)
That's not a solution
You wrote "embed text files for side-by-side comparison", and that's exactly what you got. Write "proper, kawaii as fuck diff, with colors, little +/- thingies and all" if that's what you want. I'm not psychic.
What the user and the developer expect is a properly rendered webpage on 99% of browsers without any cross-browser compatibility headaches.
What the user expects is what he/she wants to see, which is not necessarily the same as the developer. I really wish "web developers" would stop believing that what they designed their page to look like is absolutely what their users want. I don't want your dark grey on black text in some horrible tiny font. I don't want your pointless JS animated puke crawling around on the page. I don't want to see your time-wasting page transitions, fancy CSS effects or other brainless tripe. I don't care if your divs are a few pixels off in browser X or Y or Z, or that the colours aren't quite the same. I want to see your substantive content, the text and images that actually have an informative purpose. If I can see that in some older browser despite it looking very different from what you see, then your site is useful no matter what you think. Think of it this way: if I was searching for something (let's say a solution to some problem) and happened upon your site, do I care about anything other than the part that I'm interested in? No, so cut out all that other crap and make it easy for me to see that part. (Google's text-only cached version is awesome for this.)