Ryanair are now doing flights for a fiver one way - that's a tenner return, in case you were wondering.
As usual, many flights are not in the deal, they will come up at higher prices with taxes etc.
If you select the correct flights, there are no tax charges - you CAN buy a return fare for a tenner.
Choose your starting airport from a drop-down list "click here for more departing airports" - it then tells you which destinations are included.
Idiot's guide to follow.