Not a chip, but there are 3 options:
Piggyback Systems (CP-e Standback, Xede) -- Allows you or a tuning shop to dyno tune your car to extract maximum horsepower. Only works under WOT/Closed Loop conditions.
Reflashes (Cobb and CP-e FullControlFlash) -- Allows the throttle plate to open fully to extract maximum power. The Cobb Accessport adds pre-programmed tuning to either extract maximum power, OR maximum economy. Involves reflashing the car's computer. I have not heard of anyone running the Cobb Accessport Economy flash, so I do not know how it works. The Cobb cannot be custom tuned.
Unichip -- Adds a preprogrammed system that allows for slight horsepower increases. Can not be customed tuned without removal and shipment back to the vendor (this info may be incorrect, not quite sure). Is not an economy add-on
Try the search to use the pros/cons of each.