Is anything cheap anymore in Ireland?
Definitely go pub crawling around Temple Bar, do some shopping in Grafton Street, visit St Patrick's Cathedral, and have a pint of Guiness at their brewery (or, if during the week, you can have a pint early in the morning alongside the young businessmen of Dublin on the Liffey).
As far as clubbing goes, you can check out the Westin on Westmoreland street and watch the Irish dancing Salsa, have a drink at The Bank (be ready to shed out some major Euros) on College Green. There is also a really good club behind Bachelor's Walk, but I forgot its name.
> You can always get into a drunken brawl with the Irish