I just wrote a parallel resistor value calculator, and a resistor colour code calculator. There are lots of them on the web, but most of them seem to have a 1990’s era user interface, where you need to enter values into separate fields and then click on the “Calculate!” button. Blech.
So, I rolled my own with simple jQuery goodness. The parallel resistor calculator lets you type in all your resistor values (as many as you like) into a field, and the total value shown is updated as you type.
The colour code calculator is just coloured buttons that you click, and as you click, the value shown is updated.
Here’s a direct link to just the tools, and here is the same tool embedded to this page: