Sorry for this but I seemed to have forgot how to change a particle in a way so it shows a different halo like object from the default halo. I know it could have something to do with parenting objects but I forgot how to do it.
Basically what i’m saying is say you’re playing with particles and you want them red instead of white like default.
Select the emmiter, go to the materials screen and apply the one you like! 
Hope it helps.
Caio
Kansas_15, try this:
Make rain tutorial on ::feeblemind.org:: (sorry for the self promoting)
In this tutorial , I parented a water drop to the emitter. Most important thing in turning DupliVerts on for the emitter for the object to be duplicated instad of halo particles…
But I really don’t understand the color part of your question: once Halo is activated in the Shaders tab of the Shading (F5) menu, then you can change at will the color of the Halo in the Materials Tab %| And AFAIK, if you use dupliverted objects instead of halo particles you can only have one kind of object (one geometry,color, etc.) so no varying color.
hope this helps anyway
I found out how to do it, didn’t think it was that simple, guess it’s just using objects for particles and not halos that require parenting.
And I can’t read the tutorial anyway, it’s not in english.
Actually, it IS in english… The French part is in normal style, and english part is in italic style. I wrote this for both french and english speaking communities, and this is the same for the whole website. Just read further past the few first words