I'd like to be more aware of the current draw in my house. This could help
me locate appliances I forgot to turn off, or device that draw large current
even when turned off, or hidden current leakage.

The easiest way is probably to add some sort of meter to the main electrical
panel. However I don't feel like rewiring the panel for this.

Are there circuit breaker with built-in amp meter? I guess the meter would
have to be very small. If such thing exists it would be the simplest
solution. Or it could transmit the reading via powerline (x10 or insteon)
that can be read with a PC interface.