Shannon Airport (IATA: SNN) is one of the Republic of Ireland's three primary airports along with Dublin and Cork. It is the third busiest airport in the Republic of Ireland and the fourth busiest on the island of Ireland after Dublin, Belfast-International and Cork with 2.6 million passengers in 2009. The airport is located in Shannon, and mainly serves Limerick and the mid-west of Ireland.
Here are some of the major Airlines that service Shannon Airport:
Aer Lingus Regional operated by Aer Arann
Delta Air Lines
FedEx Feeder operated by Air Contractors
The above mentioned information is taken from: http://en.wikipedia.org/wiki/Shannon_Airport