I love languages too. I recommend you start learning Mandarin as soon as you can, because I waited and waited because I thought it would be too hard, until I finally just decided to learn it, though if I started earlier I could have been much further by now. German and French are my main second languages, and it seems that you are trying to improve those, we could talk to each other in French or German if you want to (though I must admit that my French is much better than my German!)

You speak Japanese? That's pretty cool!

I speak Spanish, French and English.

I interrupted my Japanese classes a few years ago and plan to resume rather sooner than later.

And I also want to learn either Korean or Tagalog, but most probably Korean.

I am also a language buff myself.

I am from Norway, so I speak Norwegian fluently. With that comes close-to-fluency in both Swedish and Danish as well, and a little bit of Icelandic (basically seems like the same language as old Norwegian)

I consider myself pretty good in English, even though I am a much better speaker than writer.
I live in Japan and work in a Japanese company, so I can speak Japanese, although not fluently, yet. Much better reader than speaker.

I took French and Spanish for 5 and 3 years respectively.
I have lived in Italy for a year.
But I am not a good speaker of these languages, basically reading and writing and grammar knowledge.

Since German is close to English and Norwegian, I can read and understand parts of it, although I have never studied it.

Should I decide to take up a new language, I want to do Greek, Russian or Korean and of course German!

I love languages :3 Planning on being a translator so I'm trying to learn lots of them.

Speak-
English (Native)
Japanese

Studying-
Indonesian (Only really focusing my efforts on this at the moment :P)
Mandarin
Hindi
Korean
Russian

Studied-
Pitjantjatjara

After seeing people in this thread, I have a question, outside of the US, is it common for people to know several languages well? Here in the US, you may run into immigrants who know their native language (usually an East Aisan language or Spanish) and English, but I've never met anybody who knows 3+ languages good. Where I live, some people born here can't even speak English right.   

Another question, how long would it take for someone with no prior knowledge to learn to read/speak Japanese enough to understand most things in Japan? 

Question #3: If you come from an English/Spanish background, which languages could you learn the quickest? and are most useful?

Anyway, I speak English fluently, and know some Spanish (still leaarning it) and after Spanish I will try to learn Portuguese, and either French or Japanese. 

Speak natively:
Spanish

Currently improving:
English

Yes, it is much more common than in the U.S. In fact, more than half of the people in the world are multilingual. It takes about 2200 hours to learn Japanese, so it is definitely a huge commitment. The easiest would be Esperanto, while most useful would be Chinese.

Trying to up my Japanese currently. An almost-daily diet of anime for a few months shy of the past five years has certainly helped, as did a semester in Japan and six semesters of Japanese classes (one of which overlapped with the time in Japan)

What slows me down, of course, is kanji. Almost all of my instruction was deficient in kanji...

Yeah, I imagine that the kanji is hard. I have a lot of trouble with hanzi myself.