http://www.1-language.com/englishcourse/index.htm - A very nice site!

http://www.1-language.com/eslquizzes/index.htm

http://www.englishclub.com/grammar/

http://www.common-mistakes.net/

http://iloveenglish.ru/stories/view/ochymelaya_anglijskaya_grammatika

http://www.english-easy.info/grammar/

http://iloveenglish.ru/theory/anglijskaya_grammatika/pravilnie_i_nepravilnie_glagoli_anglijskogo_yazika