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.
Calculators for electronic circuit design
gsrpn, Reverse Polish Notation calculator
A javascript based scientific pocket calculator