Forget those little Christmas trees, why not go for the USB Plasma Ball instead, this gives off a beautiful light effect and plugs into the USB port of your laptop. It gives off the same sort of light, but without you having to admit that deep down you like Christmas!
Features – Powered by an included USB cable, this desktop Plasma Ball is about stands about 6 inches high and includes an on/off switch. While it emits a very low current, it does so at a relatively high-voltage and so it does produce some EMF. Respect your plasma ball and it will respect you! Priced at $12.99
Source [Think Geek]