Airlines from DUB, e.g.:
http://www.aerlingus.com - cheap flights to several cities in Europe
http://www.airbaltic.com - flights to Riga, a very cool place these days
http://www.csa.cz - flights to Prague (and beyond)
http://www.estonian-air.ee - Tallinn is also worth a visit
http://www.flybe.com - flights to the UK
http://www.lal.lt - Lithuanian airline to Vilnius in the Baltics
http://www.germanwings.com - low-cost flights to Germany
http://www.hlx.com - low-cost flights to Germany
http://www.lot.com - Poland
http://www.lufthansa.com
http://www.malev.hu - Budapest and beyond
http://www.ryanair.com - the most talked-about low-cost airline in Europe, can be very, very cheap sometimes
http://www.scandinavian.net - flights to Scandinavia (and Finland)
http://www.skyeurope.com - flow-cost flights to Central Europe
http://www.transavia.nl - low-cost flights to Holland
and
http://www.finnair.com for flights to Finland (Dublin flts only during the summer season)