I'd define some standard 'real world' problems that can be run using open-source software, and simply take total accumulative runtime to solve them to be the score. For one benchmark, I'd suggest OpenFoam to run a Direct Eddy Simulation of turbulent flow around a bluff body. I'm sure others could come up with things in the field of cryptography, protein-folding, travelling salesmen, etc, etc.

1. Find yourself a web hosting provider that allows SSH login.
2. Use sshfs to mount your web-hosting space as a drive.
3. Use Truecrypt (or other) to run an encrypted file container on your web-hosting space.

Currently if Firefox comes across a html5 video using an unsupported codec, it already allows you to play the video in an external player or save the video. The problem is the HTML5 Javascript function canPlayType(); things like the Youtube trial detect that h264 isn't natively supported so the javascript never dynamically creates the VIDEO tag.

Downloaded the Firefox source and edit content/html/content/src/nsHTMLMediaElement.cpp.
Change the line

case CANPLAY_NO: aResult.AssignLiteral(""); break;

to

case CANPLAY_NO: aResult.AssignLiteral("probably"); break;

If you recompile the browser then join the youtube html5 beta, it will now try to serve you video via html5. At this stage the video is "protected" behind a transparent DIV so you can't right-click it. Use Firebug, or the following Greasemonkey script to delete the DIV.

// ==UserScript==
// @name youtube anti-div
// @namespace html5hackery
// @include http://.youtube./*
// ==/UserScript==

// video-blocker
function addGlobalStyle(css) {
var head, style;
head = document.getElementsByTagName('head')[0];
if (!head) { return; }
style = document.createElement('style');
style.type = 'text/css';
style.innerHTML = css;
head.appendChild(style);
}

addGlobalStyle('#video-player .video-blocker { display:none;');

You now have a version of Firefox 'compatible' with Youtube's HTML5. Currently it doesn't work with Vimeo's HTML5 beta and I haven't bothered to find out why.

Exchange rates are probably a poor method for comparison, not really reflecting the relative burden to the people who actually pay it. It might be a more accurate reflection to quote the figures relative to local prices for a basic item.