Yes, under the right circumstances.
We frequently hear that nothing can travel faster than the speed of light. This is a bit of short-hand, what it usually means is that 'no information can travel faster than the speed of light in a vacuum'.
It is possible to make groups of light beams that work together to make a pulse of light that travels faster than the speed of light, but no information can be carried by this pulse.
When light travels through a medium, such as air or water, it's speed while travelling through that medium is less than the speed of light in a vacuum. This is still referred to as the speed of light, but would generally be discussed using scientific nomenclature defined in the text or discussion. For example, c0 ('c' with a subscript zero, I don't know how to type that in this box!) could be used to refer to lightspeed-in-a-vacuum. The lightspeed-in-media could be referred to by 'c' with a subscript number relating to how much the medium slows light down from c0 (this number is called the refractive index), or a subscript referring to the medium name could be used eg cW for lightspeed-in-water.
Faster-than-light speed is usually called superluminal speed, while theoretical particles that are faster than light are called tachyons, which comes from the Greek for 'swift'. Superluminal doesn't refer to a specific speed, just anything above c0, and a tachyon is any particle with superluminal speed.
In any given media it is possible that different light beams can travel at different speeds. Factors that can affect the speed of light in a media include the frequency of the light, more commonly called the colour of the light. In that respect, one beam of light can travel slower than another beam in the same medium. This only works in a medium though, in a vacuum light always travels at c0. In a scientific discussion or calculation, a more rigourous way to define the speed of light in a medium would be to define it as a function of the material's refractive index, frequency, polarisation etc. The general form would look something like:
c(refractive index, frequency, polarisation)
Obviously, this way of referring to speed is not well suited to verbal discussion.
An interesting phenomenon is Cerenkov radiation - this is a blue glow emitted when charged particles travel faster in a medium (eg water) than the speed-of-light-in-that-medium. The charged particle can travel faster than cW but not faster than c0.
