I suppose it's five if you count Irish, which like everyone who grew up in Ireland I swore off once I left school. I thought I'd never utter focal eile (Irish for 'another word' and cheekily pronounced 'fuckil ella'), and indeed there still is no reason to, really. But the strange thing is that when I tried out some Irish on Memrise, for no particular reason other than that I've become a crackwhore for that site, I was surprised at how much Gaeilge was still in the aul' noggin. It shouldn't really have surprised me: for an hour or so every day throughout my secondary school education that stuff was drilled into me. Decades later it's still there, available to be unlocked should I ever feel the need. It's a funny attitude most Irish have to Irish: so much time spent learning a language which you will most likely never use again once you leave school, but which you unaccountably get quite fond of as you get older. Ar aon nós, I've written about the vague sense of cultural je ne sais pas that I get when I think about Irish here on this very blog.
Mind you, the same could be said for French. French was once going to be the diplomatic language of the world, the language of Europe, the language of international relations, the language d'amour. English, or more properly Globish, has won that race, so if you never go near France the same rule of irrelevance applies to la belle langue.
But it seems to me to be missing the point to say that a language is irrelevant. I live in Australia, so maybe everything except English is irrelevant to me. Go to Spain on holidays, Bali, or Greece, and you can get by perfectly just with English. Are Spanish, Balinese and Greek irrelevant languages for an anglophone? Broaching the question of why learn a language is an exercise in futility: you never really have to learn any language other than the official one of the country in which you live, and even then you can get away without much fluency depending on your family network and how much you care to join in society, so there's not much point in writing about it although I did give it a shot recently.
Language learning websitesI've completed Spanish and French on Duolingo and while I wait for them to get Mandarin up there I'm brushing up on my very rusty German. The stuff Luis von Ahn comes up with inspires me; check out the TED Talk where he introduces Duolingo.
Likewise Memrise. Here is a site whose every page, practically, is just a single question, but which to me has become indispensible. I love the mems, and reading "Moonwalking with Einstein" which actually features the founder of Memrise, Ed Cooke, gives you an interesting way of looking at the whole memory improvement thing, pretty important when learning languages.
It's hard to tell where the social layer ends and the gamification layer starts with sites like these. You can friend people, so that's your common-or-garden social stuff, and the gentle competition works. I might want to see how my friend Luis is doing on Duolingo this week, for instance. I wrote about how Duolingo is as much a game as it is a way to learn a language recently.
A site I've really jumped into recently is italki. The end goal of italki is to connect to people on Skype: I've had tons of chats (both paid-for and free) with Chinese and Spanish speakers. It's interesting: with Chinese people, you end up graduating to WeChat, simply because that's where they like to hang out. On any day of the week, I might have a small chat with one or two Chinese friends (in Beijing, Tianjin, Shenzen, or Malaysia) on WeChat, or check in with a South American buddy (time difference is a pain there, unlike with Chinese friends) on Skype, all found via italki. I've even written an article recently about Spanish for italki: ¿Qué tal llevas los acentos?
ClassesNow, when I say I'm kind of learning 5 languages, it's not like I'm going to night classes (well, I am for Greek) or have some upcoming examinations or anything. Simply to be able to read a book originally written in another language well enough to understand it is a great pleasure. While in Spain recently I bought La sombre del viento, and recently, finally, finished it, which I wrote about on 'Koukla House', my wife's blog. Having said all that, I joined the Alliance Française de Brisbane recently and to my great surprise one fine morning at work I got a call from Aurore to assess my ability (intermediate, B1.4/B1.5) which was a bit intimidating, but in a charming French way.
The thing I'm probably proudest of is a Tertulia Español me and another Irish IT head, +Karl O'Neill, have managed to hold together for the last 2 and a half years. Fellow founder-member +Sandra Palacio from Colombia is our teacher, although her teaching duties usually extend simply to talking with us about God knows what, often accompanied by the Mexican contingent of +Luis Franco Marin and +Miguel Angel Alvarado Molina. You need native speakers if you want to proceed conversationally, one reason the French conversation meetup group I used to attend only got me so far: a severe dearth of actual francophones. Despite the difficulty of trying to keep up with a trio of South- and Central American speakers in full flow, there's no better way to improve.
Recent and ongoing language influences are Benny the Irish polyglot, and a great book called "You Are What You Speak" by Robert Lane Greene.