Dublin Pass

It completely depends on what you want to do/see in Dublin. Take a look at the costs of the various things you might want to visit that are covered by the pass to see if it would save you money. The last time I looked, many of the things covered by the pass are free anyway -- the pass provides things like 10% off in the gift shop or whatever, in that case -- or things I wouldn't be interested in, so it wasn't a good value to me. You might feel differently.

At visitdublin.com the pass is 15% off now. I got mine at 20% off and after doing the math for the sights I intended to see [ and adding in shipping] I found that I would break even so I got it as to have some of the trip paid for in advance and to be able to pop into a few places I had not planned on visiting if that turned out to be convenient. Also the hop-on-hop-off bus tour I had planned to take was discounted as well. You get a few free postcards and some other discounts as well but not sure it is a deal at full price.