I'm not sure of the species but this little (~8 mm) jumping spider is very common in Riverside, California in June and July.   I'm fairly sure it's a male, because of the bright coloration and fairly elaborate palps.   The one at the bottom right of the page is eating another, even smaller spider that came too close (for a sense of scale, the animal is sitting on a brick wall).
            Images of other jumping spiders are here, here, here, here, here, here, and here.