Putter designer Guerin Rife makes great putters. His lines of RIFE putters are: the Two Bar Putters (available in a Mallet or Blade), the Island Series and the IBF Tour Series.
The series I'm most interested in is a Two Bar Putter blade, not the mallet. Rife uses an unusual RollGroove Technology that gets the ball rolling faster with a true forward roll. This lowers the friction with grass. Here's a look at the RIFE Hybrid Tour Blade:
A "regular" putter has 3 to 6 degrees of loft on the face. So when you hit the ball it jumps off the ground a little and has a very slight back roll. When the ball 'lands' it causes it to skid on the putting green before the back roll becomes a forward roll. During this "skid period" the grass grain can cause the ball's dimpled surface to slightly change its direction and speed. I think this illustration show it best:
For more info on Guerin RIFE putter or to buy one, simply go to the Edwin Watts and type in RIFE in the search box and hit GO... or go to The Golf Warehouse and select Guerin Rife in the manufacturer drop down.