Looking for the cheap flights from Ireland? If so then Ryanair is still unbeatable in this area. Their website is simple and easy to use and the bargain hunter will be rewarded if checking the site frequently for specials. Read the fine print though as one may be caught out with hidden taxes/charges. Even taking this into account flight prices are extremely cheap with flights from Dublin to London as little as €14.99 (excluding charges).
Aer Arann is an Irish airline in a similar vein to that of Ryanair's,when it comes to low cost flying. Offering cheap flights also but with a much more limited choice of destinations. It currently only operates to British airports and two French bases (Rennes and Loirent). Still quite useful to pick up a cheap flight from if one didnt mind travelling further from destination.
When searching for cheap flights from Ireland and one is not too fussy about the choice of carrier then I would recommend the website cheapflights.ie. It is a useful search comparison tool when scouring the web for the ultimate bargain. It boasts flight comparisons from more than one hundred travel providers. It also provides a hotel search facility.
Gohop.ie is also another great search engine I would recommend. Not only does it provide flight and hotel search facilities but also car hire, package holiday and bundled togther,flights and hotel.
Of course general rule of thumb when booking flights anywhere is to pick a midweek arrival/departure date if possible,(Wednesday being the cheapest,followed by Tuesday).