I have reached usable fluency in English, Esperanto, Hebrew, and to some degree Spanish--and I am going to south america for a few months to sharpen that one soon.
Hebrew was originally a desire from my once-religious days; later it became a gateway to cheap university.
Esperanto was my gateway language, and a fun theoretical pursuit. I learned it principally to aid in learning other languages after it, and I have no regrets. It still makes for fun in its own right--reading the news on liberafolio.org, chatting on an Esperanto IRC chanel, and just one more quirky thing to engage in.
Spanish is more complex... but if nothing else, it's the second most spoken language in the world (after Mandarin) (yes, English is third, probably, and not by much), which is useful. I want to be able to escape to Latin America if necessary someday, perhaps. And I grew up with a lot of latino culture around me in my youth, and so feel some connection to it.
I also learn Japanese on the side, on and off. Learned all the Hirigana at one point, though it's only half-there right now. I could pick it up again if I wanted to, but I'm instead focusing on the speaking approach and using a Pimsleur course for it.
I also know some Latin from some studies done before I realized Esperanto existed, and some token French and Arabic. After that, it's just a couple words here and there in various languages that aren't enough to deserve mention: Russian, Chinese, Icelandic, Italian, Brazilian Portuguese, Finnish, Swedish, and so on...
I love languages. They're the perfect mix of intuition and logic, complex yet attainable, and I have a knack for accents and languages as a whole--success is enjoyable. And they garner a great deal of respect.
Also, in regards to the Moroccan statement above, about them all knowing 5-10 languages--Bullshit. Except for a handful of rare hyperpolyglots in the world, an average-intelligent person can only maintain reasonable fluency in 7 or so languages max; beyond that, the maintenance itself is too high. Jerusalemites are the most language-happy people I've run into yet, with speakers of 3 languages not being uncommon, and 4 not being so rare.