majhi:
Thanks for all your input guys. I think I have settled on this item as it can also provide power to the Uno itself with a 5v rail:
http://www.sainsmart.com/16-channel-5v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.htmlSeems simple enough.
That still requires 16 pins to run and it's fairly big and heavy. There are plenty of methods to run a pile of LEDs that are a lot less complicated, cheaper etc. I would go with a i2c LED controller it's easy to get 100's of LED's off of 2 Arduino pins and generally only needs a pair of resistors for the i2c buss. The cheapest is a pack of transistors one per pin, connect between the LED's and the +5v rail.