There are a variety of places that fit the bill, varying really according to what you consider 'small' and what time of year you go. Some seaside places are very packed in summer, but almost empty in winter. Some suggestions:
Dunmore East - a pleasant little coastal town, more a village really, with some nice restaurants and bars.
Youghal, Co. Cork. A traditional old seaside town, a long beach, some very nice traditional old guesthouses.
Kinsale, Co. Cork. A beautiful (but expensive) medieval town near Cork City. Famous for its seafood restaurants and old style streets. Its quite buzzy all year round, especially when there is a big yachting event on.
Baltimore, Co. Cork. A tiny village (it was the setting for the film Moby Dick), which has grown quite a bit lately. Its in an amazing setting, really beautiful. Just a tiny beach, but a famous sea water lake nearby thats good for swimming. Very busy in summer, quiet in winter. Some nice old bars, but not great for food.
Clonakilty, Co. Cork. A very nice small country town - no beach, but it has great pubs and restaurants, famous for its black puddings.
Waterville, Co. Kerry. Very beautiful setting, long beach, an old Victorian seaside place. The town itself is a bit dull, not much to see or do.
Dingle, Co. Kerry. A great little town, lots of boat trips - nearest beach is about 8km away. Great walks and cycles in the area and lots of old pubs, but its very touristy in the summer - prices go up accordingly. You need to book in advance to get into one of the better guesthouses (some of the more modern hotels/guesthouses aren't so nice).
Lahinch, Co. Clare. An old seaside resort, a little run down and fading, but its recently become very popular with surfing types. A lovely sheltered beaches and great walks to the north in the Burren region.
Enniscrone (sometimes spelt Inniscrone) in Co. Sligo. A traditional seaside town, but it faces north so it can be pretty cold sometimes. Great surfing and traditional seaweed baths. Not great for pubs or restaurants.
