Hi!
I tried to use an N-Mosfet to switch some self-adhesive LED band specified with 12V / 0.5A. The Mosfet (BS-170) can drain 500mA continuous. Works perfect, and it can be easily used with one of the Relay Sketches. Add an Pulldown Resistor, so the Gate won't keep float in Case of Reset or while Flashing.

It's pretty simple, and you can save some Relays ;)

Greetings