What is the recommended type of tire for riding on wet pavement? I am commuting in rainy Seattle, and the rain has started.  Right now I have Continental Gatorskin tires on my commuter, but yesterday I noticed I was braking to stop the wheels and skidding quite a bit on wet roads.   I know I can gradually adjust braking on front and back to come out of the skid, but I was wondering if i should replace my tires to get a little more grip.  My LBS seems to think thin slicks are fine however.  Is there a study or data on tire types on wet pavement?
If you are riding on the road, slicks are fine in the wet. If you need to go over any mud, etc. then you'll need something else.

From Sheldon Brown:


  Bicycle tires for on-road use have no need of any sort of tread
  features; in fact, the best road tires are perfectly smooth, with no
  tread at all!
  
  Unfortunately, most people assume that a smooth tire will be slippery,
  so this type of tire is difficult to sell to unsophisticated cyclists.
  Most tire makers cater to this by putting a very fine pattern on their
  tires, mainly for cosmetic and marketing reasons. If you examine a
  section of asphalt or concrete, you'll see that the texture of the
  road itself is much "knobbier" than the tread features of a
  good-quality road tire. Since the tire is flexible, even a slick tire
  deforms as it comes into contact with the pavement, acquiring the
  shape of the pavement texture, only while in contact with the road.
  
  People ask, "But don't slick tires get slippery on wet roads, or worse
  yet, wet metal features such as expansion joints, paint stripes, or
  railroad tracks?" The answer is, yes, they do. So do tires with tread.
  All tires are slippery in these conditions. Tread features make no
  improvement in this.


Also worthy of note is:


  Car and truck tires need tread, because these vehicles are prone to a
  very dangerous condition called "hydroplaning." This happens when
  driving fast in very wet conditions, which can lead to the tire riding
  up onto a cushion of liquid water. When this happens, there is a
  sudden and total lack of traction.


Bicycles can NOT hydroplane because:


A bicycle tire has a curved road contact. Since a bicycle leans in
corners, it needs a tire with a rounded contact area, which tends to
push the water away to either side.
A bicycle tire is narrower, so not as much water is in contact with
the leading edge at once.
The high pressure of bicycle tires is more efficient at squeezing the
water out from under.
At high speeds, hydroplaning is just possible for car tires, but is
absolutely impossible for bicycle tires.