with colored light, try reducing the radius of intensely colored ones (raise the wait value to 2 or more).
You have to play around with wait values really.
Also try combining white lights with the blue ones.
Although light blue and light-medium yellow seem to usually work well - watch for pure colors (red green blue) and reduce their radius / lower the brightness. The blue spot on the right side of shot 50 is kinda intense.
For a strong colored light effect like with lava or big flames, keep the brightness under 250 (avoid the washed out effect / clamping) and increase the radius instead / put several point lights spread out over an area instead of cranking up the brightness.
You can have subtle colore variations with this latter approach / combination with white.
http://kneedeepinthedoomed.wordpress.com/2010/11/07/orange-light-green-walls-far-out-experiences-with-colored-light/