1Keyboard to rule them all!
Eyal Wiener's awesome 1keyboard allows you use your Mac's keyboard and mouse to control other devices. Since it's using Bluetooth, you're not limited to computers, any HID-compatible device will work. I'm using the app to quickly enter text on my development Nexus 4.
1Keyboard is in beta right now, and while the responsivenes of the mouse can surely be improved, it's already a welcome addition to my Android development flow.