Useful links.

http://www.abc-english-grammar.com/
http://alemeln.narod.ru/
http://www.alleng.ru/
http://www.audio-class.ru/
http://www.breakthrough.ru/
http://www.bilingual.ru/
http://www.efl.ru/

Here's also a list of useful applications:
Test you English Vocabulary
Test your Grammar
Practice English Grammar