Two smoke systems that collide and are at different heats so when they mix they change colors
[youtube http://www.youtube.com/watch?v=XOf-kLMedkc&w=560&h=315]
Ok, so i spent two or three hours this evening looking at how to create a similar effect with fluids. Right not, there is not an easy way to do this. The only possible way that would still look realistic is to create a fluid simulation with two inflows or fluids. Then after you have created and bakes that, create a particle system for each inflow and set the physics to fluid and use dynamic paint to change the color of the liquid. I don't think even that would work and i look forward to the day when blender rivals realflow in these kind of things.
thanks dude, i was wondering that can we do something like that for the fluids too?