This is totally awesome, and definately has the potential to be one of the best logic simulators out there (especially as it's free).
A few suggestions (to help you make it the best):
-A way to snap wires to go either vertical or horizontal, maybe by pressing ctrl.
- A way to edit and delete chips you made previously.
- Some way to get more space such as zooming or moving the work area.
- A way to group wires and inputs into a single wire or bus line.
- A decimal representation of negative numbers.
- Moving the mouse over a chip input shows the input name.
Also there is no decimal representation of outputs, and the input names don't show.
Something else that might be interesting is adding a simulation rate to slow down the speed like you demonstrated in the "How do computers remember" video.
I'm excited to see where this project goes. Keep up the good work.