I used to, yes...but then I found a language-sharing site. That put me in touch with quite a few people in different Spanish-speaking countries (my second language of choice), and I learned a lot faster and a lot more practical aspects of language from them. I haven't used online exercises since then, but might soon for learning Russian -- Russian is my husband's first language, but I'd like to work up a bit of base knowledge before expecting him to teach me more.
For me, English is my second language, and luckily, I do not really need to search the web for any learning sites, as my university offers such courses for credits. That being said, I learnt a lot during my time at various gaming forums - folks there had been very nice back when my English was very, very simple and rather crude in its structure, but since then, I mostly stay at various communities to keep my knowledge of the language fresh and expanding in various fields of interest.