Ryanair actually seem to be doing a good deal for once!! If you choose to fly midweek during March, April, May & June, you might be able to fly for under a fiver, including taxes :)
I've just booked flights, London Stansted - Dublin During May for only £4.99 including tax!! Bargain!!
Great deal in my opinion, but be quick!!
It is on the homepage, below the fly free to germany bit