Beer in America is generally consumed at a temperature too cold to taste the complexity of flavors in most beers. Here is general guide of the ideal temperature to dink beers by style.
 

List by Style:

Altbiers: 50-55° F
Amber Ales: 50-55° F
Barley Wines: 50-60° F
Bitters: 50-55° F
Bocks: 45-55° F
Brown Ales: 50-55° F
Dark Lagers: 45-55° F
Dunkels: 45-50° F
Helles: 45-50° F
Lambics/Gueuze: 50-60° F
Lagers: 38-46° F
Pale Ales: 50-55° F
Pilsners: 45-50° F
Porters: 50-55° F
Schwarzbiers: 45-50° F
Scottish Ales: 50-55° F
Steam Beers: 50-55° F
Stouts: 55-60° F
Trappist Beers: 50-60° F
Vienna Lagers: 50-55° F
Wheat Beers: 45-50° F
Wits/Whites: 40-45° F
 

List by Temperature:

Lagers: 38-46° F
Wits/Whites: 40-45° F
Bocks: 45-55° F
Dark Lagers: 45-55° F
Dunkels: 45-50° F
Helles: 45-50° F
Pilsners: 45-50° F
Schwarzbiers: 45-50° F
Wheat Beers: 45-50° F
Altbiers: 50-55° F
Amber Ales: 50-55° F
Barley Wines: 50-60° F
Bitters: 50-55° F
Brown Ales: 50-55° F
Lambics/Gueuze: 50-60° F
Pale Ales: 50-55° F
Porters: 50-55° F
Scottish Ales: 50-55° F
Steam Beers: 50-55° F
Trappist Beers: 50-60° F
Vienna Lagers: 50-55° F
Stouts: 55-60° F