What most surprised me about the Irish property market, is that the majority of Estate Agencies are 'seller's agents'. They work exclusively for the sellers, promoting their properties and brokering the sale, however, they don't assist buyers in finding a property.
While according to the Estate Agents list on MyHome.ie, there are currently 335 Estate Agen's offices in Dublin. It is true though that some of those are subsidiaries of the same Estate Agency, for example, Sherry Fitzgerald has 20 offices, while DNG 13.
Two great sites that pull together properties from different agencies are MyHome.ie and Daft.ie.
While those two websites are great, it's always best to monitor the individual Estate Agencies' sites too: the information presented will be the most updated and accurate. Furthermore, estate agents are more likely to call you back if you contact them through their site.
Here's a list of the best Estate Agencies in Dublin, based on my experience and research:
DNG - http://www.dng.ie/
SHERRY FITZGERALD - http://www.sherryfitz.ie/
HOOKE & MACDONALD - http://www.hookemacdonald.ie/
WILSON & MOORE - http://www.wilsonmoore.ie/
CASTLE ESTATE AGENTS - http://www.castles.ie/
SAVILLS - http://www.savills.ie/
RAY COOKE AUCTIONEERS - http://www.raycooke.ie/