She discovered a few weeks ago that by carrying a milk crate (we use it for toting her toys back to her room) to where she wants, she can reach light switches and flip them on and off. We encourage her independence, so we've had no problem with it after getting through to her that flipping the lights on and off rapidly isn't polite.
On Sunday night while the guys were switching off from Himself's computer for a HoMM4 hotseat game, she found the mini-USB plug end of my camera's connection cable (the regular USB end was plugged into my computer) and played with it until Himself said "[your] computer just found new hardware?" and noticed she'd licked the cable.
Today he let her play in the bedroom while he was getting ready for work in there and she managed to flip half the switches in the circuit box. (I was in the living room, out of line of sight.) I'm still confused since those switches are hard for me to flip and he claims he had no idea she'd done it. At any rate, the master bedroom is now permanently off-limits to her.
I'm now thinking about new ways to render any potentially reachable wiring in the house safe from her since we've already installed child-proof caps on all the outlets, kept power cords for appliances either wholly out of reach or attached to furniture they're sitting on (e.g., my computer's cables to the table leg) and drawing blanks. I expect this to be a character-building experience for all of us.