The original Irish coffee, according to lore, was invented by Joseph Sheridan, a head chef at Foynes, County Limerick. Foynes' port was the precursor to Shannon International Airport in the west of Ireland; the coffee was conceived after a group of American passengers disembarked at the airport on a miserable winter evening in the 1940's. Sheridan decided to add some whiskey to the coffee to warm the passengers. After being asked if they were being served Brazilian coffee, Sheridan told the passengers that it was Irish coffee.
The correctness of who first introduced Irish coffee to the United States, however, is disputed. Stanton Delaplane, travel writer for the San Francisco Chronicle, claimed to have brought Irish coffee to the United States when he convinced the Buena Vista bar in San Francisco to start serving Irish coffee on November 10, 1952. However, since around or before that date the beverage has been served at Tom Bergin's Tavern in Los Angeles, where a large sign reading "House of Irish Coffee" has been in place since the early 1950's.
Making Irish coffee is dead easy: make a regular cup of coffee, add some whiskey (according to taste), at least one teaspoon of sugar, and top off with a dollop of the cream. (The sugar, even for those who don't usually take sugar with their coffee, is necessary for the cream to float on top.)
Different variants of the beverage have evolved over the years, such as Baileys coffee, which uses Baileys Irish Cream in place of the whiskey, and Kentucky coffee, which substitutes Kentucky bourbon.
The Foynes Flying Boat Museum holds an annual Irish Coffee Festival in August which includes the World Irish Coffee Championship in County Limerick. The celebration includes participants from the world's best hotels, restaurants, and bars.