Recently I whipped up a small online calculator app BruttoNettoGehalt.at (Brutto Netto Rechner, Gross Net Calculator) for fun.
The most interesting insights were
– cross-browser Javascript compatibility still sucks. I had to make several runs with IE (6, 8, 9, from worst to acceptable) to get things running, Chrome, Firefox, Safare are a breeze
– Javascript minification (I used the Google Closure Compiler) works nice, and also provides some minimalist form of obfuscation
– putting the page through the HTML Validator can save some major headaches caused by broken layout
– Tax and social insurance legislation is absurdly complex, and not easy to find in a form that’s easy to transform into code
– it’s easy to beat most existing websites in clarity and usability, but hard to beat the in pagerank