FindMyPast Ireland has a St Patrick's special offer of 50 free credits to use on its database. Just click the logo, follow the 'Redeem Coupon' button on the home page and use the code STPATRICK. You can then register and start searching.
Alternatively, get yourself down to the St Patrick's Festival Irish Family History Centre in central Dublin, where you can search all FindMyPast.ie's records for free over the weekend. You can also get guidance from genealogical research societies, Eneclann, militaryarchives.ie and others while you're about it! There are also lectures every day.
The Centre is being held this weekend only at the Discover Ireland Centre on Suffolk Street (St Andrew's) and is open today until 5pm, on Saturday from 10-5, on Sunday from 11-4, and on Monday from 11-3.