Below websites are quite usefull to study English for me.

http://grammar.ccc.commnet.edu/grammar/
This enables me to learn English grammer variedly.

http://www.bbc.co.uk/worldservice/learningenglish/index.shtml
The movie makes me laugh and try to open the page iteratively.

http://www.phrasebank.manchester.ac.uk/
I'll use this page when I try to write an academic report.