This site has a variety of grammar quizzes:

http://esl.about.com/library/quiz/blgrammarquiz.htm

Practice with grammar quizzes (bilingual quizzes too) from beginner to advanced level:

http://a4esl.org/

 Here you'll find grammar and vocabulary lessons, tutorials and exercises:

http://www.englishpage.com

This website includes a variety of exercises, even audio- and video-based practice, and tests:

http://www.learnenglishfeelgood.com

'The Big List' from the ESL Department at Long Beach City College includes grammar lessons and exercises for different proficiency levels:

http://esl.lbcc.cc.ca.us/mmcportal.htm

5 Minute English has grammar lessons (including some YouTube videos) and more:

http://www.5minuteenglish.com

This website offers free grammar lessons from beginner to advanced levels and it includes YouTube mini-lectures:

http://www.learnamericanenglishonline.com

Dave's ESL Cafe lists many grammar exercises:

http://www.eslcafe.com/grammar.html

This resource for ESL students includes quizzes, language tips, and useful articles about grammar rules:

http://usingenglish.com/students.html

This is a list of adverbs and adjectives with the same form. There is also one cloze exercise to practice the words:

http://www.eduhi.at/dl/adverbs_and_adjectives.htm

This is a list of adjectives ending in "-ly":

http://www.angelfire.com/wi3/englishcorner/vocabulary/lyadjs.html