Learn Japanese with Japanesepod101.com ¼*°*´ëÇб³ Çѱ¹¾î °*ÁÂ
I'm an aspiring polyglot and after I've spent a lot of time trying out various podcasts and learning software I came to the conclusion that a good textbook with audio is still the most important thing for my language studies. So I would recommend a traditional textbook as the basis of you language studies. I love the Assimil books (learnt most of my Japanese from Assimil).
A good audio course is Pimsleur ... (you can find Pimsleur tapes for most languages), it's a great introduction to a language because it forces you to use the language and create your own sentences. You won't learn very much, but the confidence and the feeling for the language that you will acquire can be a strong fundament for you language studies.
I don't really like Rosetta Stone. You can learn some vocabulary and it's a lot of fun playing around with, but I doubt that it will get you far. (despite what it says, you can learn much faster with a textbook and some audio CDs). But if it can boost your motivation, play around with it. Motivation is probably the single most important thing when it comes to language learning.
I love Japan and the Japanese language and I still have to motivate myself constantly to keep up with my studies.
I'm working on a language learning blog right now (actually an older blog that I'm about to revive).