Technologist Jim Paris has created a simple terminal emulator for Python which is quite useful - it allows connection to two or more device in the single window. Setup is via the command line, and each device connected can be colour-coded to save confusion. What this has to do with Arduino is quite simple - when you're prototyping with more than one board at the same time - you no longer have the confusion about which window is for which board.
If you're looking to work with multiple Arduino Leonardo-compatible boards at the same time (or even one!) - look no further than the Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound and knock detection: