Moving to Japan; need better language skills

So I recently found out that I will be moving to Japan sometime early next year for work related reasons.

I do speak a little Japanese and know enough to get around without too many problems (I hope)... But I have to be honest, I'm absolutely terrified. I've started Rosetta Stone and I'm up to Unit 5 on Level 1 and I have yet to learn something new/useful.

People who are native speakers of English and are now fluent in Japanese, how did you learn the language aside from going there?

I want to get A LOT better at it before I actually go. Not fluent, but I'd like to be able to hold a semi-decent conversation.

Also, I fucking suck at kanji. (I think I know somewhere between 200-250.) I'm reading Heisig, but is there anything else I could be doing for that?

I'm sorry, but I'm horrified of going to live somewhere for 2 years where I can't talk to people outside of work. (I know I had the option of declining, but it was too good of an opportunity to pass up)


tl;dr I'm moving to Japan in 6 months. How can I drastically improve my language skills before then?

mixi requires an e-mail adress from a Japanese mobile phone company now, so I guess that's out for you. You could take a look at http://lang-8.com/ if you want something like that. It's not for Japanese exclusively but about 90% of it is anyway.

Also you should probably take a look at www.alljapaneseallthetime.com - you may or may not buy everthing the guy says (this site is capable of stirring up a lot of rage) but he does have a lot to say about learning Japanese very intensively over a short period, so I'm sure you'll get something out of it.