I learn my languages from evening classes. Its pretty good to learn as a group with people at the same stage/level, but you have to put in *serious* homework time to make it worthwhile.
I've not used rosetta stone etc, as far as I know these teach you prefixed sentences, whereas I prefer to learn grammar, verb conjugation etc so I can form my own sentences.
for the record, english, dutch, flemish (dialect of dutch), german. Learning French in evening classes and want to learn swedish but no classes locally, so would be interested to see how you get on outside of classes, might be useful.