Hi guys, I'm still lurking
and saw that Salsa and Zumba have come up as suggestions.
I agree totally with Mood, - Zumba is more of a fitness thing than anything else, but as a guy, youll be in demand at Salsa classes, due to there being a maybe 60/40 or 70/30 split in the classes I've been to in Dublin.
The age group seems to be 20 to 45, lots of other nationalities as well as Irish, in my experience,- you'll make great friends, get invited to parties, and best of all, you'll (after a few weeks/months) be able to walk into a Salsa club anywhere, and ask the pretty girl up to dance without a thought.
Batchata (another dance) is often taught as well, it's easier than Salsa, and gives you the chance to get in close as you get to know someone better.
There are classes all over the country, word to the wise,- if you can find a class that does "Cuban" salsa, go for it, it's less silly twirls and more about the rhythm, also, you change partner regularly, which means you get to meet everybody.
Depending on age, set dancing can also be good to meet someone, I've noticed the age profile has gone up a wee bit since I used to be involved.
The thing with dancing in groups or couples is the "let's get through this together without falling on our faces" kinda vibe which promotes closeness quicker than other night classes. Also, the physicality of holding someone's hand or shoulder is pretty cool if you haven't done any coupled dance before.