Well, as dull as that title may sound, it is very descriptive. I figured out while playing last night that you can make the effect of a droplet of water splashing against a hard surface or pool of water using particles in Carrara. If you set up a particle system with particles that die upon collision with another surface, then also set up spawning with an angle of 70 +/- 10 degrees or so, it makes a pretty nice splash that expands and disappears quickly. You have to adjust the various parameters to get the right size, speed, and shape, of course. I also find that if you create a plane and make the plane the particle generator, you can simulate rain. Of course you have to set the initial velocity of the particles to be negative, like maybe -20ft/s. You should not use the plane primitive, though. I think it works better if you create a vector object and make a planar grid. The plane primitive does not have many vertices, and I think that means that particles can spawn from fewer places. If you generate a planar grid, in the modeling room, I think it gives a more even distribution of generated particles.
Try it out!