Scandinavian fly from Dublin to Stockholm's main airport (Arlanda) pretty much every day (they also offer services via Copenhagen)
FlyNordic ( http://www.flynordic.com/ ) also fly to Arlanda airport from Dublin - not that frequently though - I think only twice weekly.
Ryanair fly to "Stockholm" Skavtsva and "Stockholm" Vasteras but only from Stansted - not Dublin. Neither of these airports are particularly close to Stockholm at all.
They used to fly direct Dublin to Arland Stockholm.
Not as cheap as Ryan Air maybe but then again go straight to Arlanda and then the Arlanda express (twenty five minutes travel time) direct into Stockholm city centre for about €20 .
J