Rosetta Stone works very well, especially if you get the software and practice on a regular basis.
I sub at the Boise Language Academy, which is a school for new immigrants to the United States who are not fluent English speakers.
Today, the teacher I subbed for has two classes where she takes the kids once a week into the computer lab and they do the Rosetta Stone for English. The kids wear a headphone/microphone headset and they do the lessons independently. This is just part of their "English Language Development" class, but it's quite interesting.
I was sitting in the back of the room while I listened to a Vietnamese boy said, "What are you doing?" over and over again until the software decided it was satisfactorily pronounced. At one point, he took his headset off, (after saying it about twenty times), and said to the boy next to him, "will you say 'what are you doing?' for me?"
I was in the back of the room, kind of just watching them, cracking up.
Later on in the day in a different class, a girl from Iraq was stuck on the same thing. She was getting irritated, and I thought she was saying it just fine, and she kept looking at me like "WTF?"
Finally, in a really, really high-pitched voice, she said, "what are you doing?" and it went to the next exercise. We laughed.
So, Hotplant, long story longer: Rosetta Stone is used in the public schools in Boise for English Lanugage Learners. I'm thinking it works pretty dang well.
Oh and more: German is pretty hard for English (language 1 /L1)speakers to learn, even though English is a Germanic language. German L1 speakers can read Old English easier than English L1 speakers.
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What I came in here for:
I'm STILL reading Grapes of Wrath. I've had a bit of ADD with books lately, but I'm almost done.
Man, I need to finish this book up, because it's starting to really depress me, (I'm almost done, I think I have less than fifty pages left). I LOVED it the last time I read it when I was in high school...
edited: I left the Joads in their high-ground barn...I finished it.