The single best place to find all open roles in Dublin is on indeed.com or glassdoor.com if you're looking for more info on company culture, salaries and interview styles.
The big US employers like Microsoft, Google, Facebook, LinkedIn etc are all hiring. Native Northern European languages are always in strong demand for sales and support roles. They tend to be excellent employers in terms of career progression, perks, etc.
There are some fantastic smaller companies hiring in Ireland too. As of Jan 2017 my company (Zartis.com) is helping some of the best with their recruitment. For example, we work with StoryToys in Dublin. They're a developer and publisher of kids educational content. We also work with companies like Looker.com, a data analytics platform, and Udemy, the world's leading online learning platform. If you prefer a smaller town we also have excellent clients in Cork including Nginx, the web server and load balancing system for large scale web sites.