These lights are a 5' waterproof strip of RGB LEDs from Elemental LED. They can change color with a few different patterns and can be controlled with a remote. The best for long term use for me is the slowest color-fade setting. It shows off what the lights can do and draws the least attention to itself for extended viewing.
I just dropped these lights into the tub and the effect works great. If you want a cleaner look, you can drill a hole in the side along the bottom and attach the lights that way. Use a hot glue gun to seal up the hole.
That's it, fill it up with ice and drinks and you're good to go!