base64 http basic authorization encoder Encode username and password into a string suitable for HTTP authorization. Use this if you want to post to twitter or idendenti.ca from a tuxgraphics ethernet board.
Units Converter
Unit converter Convert between imperial and metric units.
Even more calculators and converters can be found at: http://tuxgraphics.org/~guido/javascript/
They require nothing but a web-browser and they work even offline. That is: you can save the HTML page locally on your computer or mobile phone and use it from there without being connected to the internet.