7 Years ago, I moved to France to work, not speaking a word of French, and I'm now a fluent speaker. The internet was instrumental in my learning French, but maybe not in the way you might expect...
First, I used the net to search for and buy a program called Linkwords (I don't think it exists anymore, it was a crappy VB program). The software sucked, but the principle worked. It was a sort of flash card system that had you using vivid imagery as a mental aid. My vocab hit around 2000 words in the first couple of weeks. It was useless for learning to speak French, but the perfect lifesaver for reading signs, product packaging, etc.
Then, I used P2P programs to find MP3s of Pimsleur French. For those not in the know, Pimsleur was a Harvard professor in the 60s who developed a system for learning languagues that mimics the way children learn. It's all about stimulating the memory at programmed intervals and it is one of the best ways to learn to SPEAK a language. (While there is writing materiel supplements, they're relatively minimal). These are quite expensive (you can spend up to $1000 for the complete set) because they work. You need to have about 1 hour a day to devote to it, and it must be somewhere you quiet that you can listen, and speak. (You need to hear yourself speaking for it to work).
Next came my traditional phase, where I spent a lot of time reading BDs (the French equivalent of Manga. BD is Bande Dessinee (accents ommitted) which means comic strip. There's a very large adult BD culture in France). From there I progressed to Harry Potter (which is a surprisingly difficult read in French, lots of flowery speech, wordplay, etc.).
After this, my French was halting, but I constantly tried, and was always asking the meaning of words from my colleagues.
Then I started watching more French TV. At the time, the number of shows that were subtitled was depressingly dismal as compare to the US (though it has gotten a bit better). Again, computers and the net to the rescue, because I was able to download DVDs (the whole multi-language, multi-subtitle feature is a godsend for language learning). What you might not realize is that a lot of understanding a foreign language is based on context. If you know it, it's much easier to guess what is being said. In a conversation, if you miss something, you can ask the other person to repeat. Watching TV or movies requires you to pay closer attention. You can rewind, but you can never get the speaker to express the same thing using other words, so you really have to understand whats being said.
Finally, thanks to the internet, I was able to find about speed dating events in my area where I met my wife. My wife speaks English (she's an English teacher) but her family doesn't, so that got me into social situations that required me to practice speaking.
Now, I had the benefit of immersion, but I think it's important to realize that the internet is not a magic bullet for learning a foreign language, no matter what companies that sell internet based language services say. That being said, however, if the internet makes learning materiels more readily available, as well as practice opportunities, I'm all for it..