Massless particles like light are limited to traveling at the speed light can travel. Refer to Wikipedia’s section on mass-energy equivalence, which is located in the Special relativity article.
http://en.wikipedia.org/wiki/Special_relativity#Mass.E2.80.93energy_equivalence_2
But particles with mass can travel at any speed. You can accelerate massive particles as fast as you like, and they will speed up. Your marginal returns will be diminishing. If you plot the energy needed to propel the particle to any speed, you will find a singularity that requires infinite energy at exactly the speed of light.
Scientists using particle accelerators have to adhere to the speed limit of light when trying speed up their particles. They may be able to increase the speed of an individual electron if energy is available. Even with all the energy stored in sunlight, there would still exist a gap between that single electron’s velocity and the speed light.