Online Number Converter (for programmers)

Look here: http://gowentgone.de/calc/

Type in a number in decimal, hexadecimal or binary. The site instantly gives you the other values and a couple of different representation of that number.

High emphasize on the representation of the numbers in different data types and bit sizes including separate interpretation of signed and unsigned numbers.

Since 2.6 with simple calculation function.

Note: there are some issues with Internet Explorer.