I really like these sites because they are so user friendly. There are the usual grammar and vocabulary exercises but as the English File series is one of my favourite resources, it's so easy to link to your lessons with me at the right level. Perfect for on-line homework!!
Excellent interactive resource - probably Intermediate to Advanced - but (e.g.) the pronunciation section is for all levels. Once you find your way around the site, there's smething for everyone (Business English, Exam practice etc) . Wordmaker is great fun (level Easy to Advanced).
Brilliant site. The best newspaper in English. Upper-Intermediate to Advanced. Something for everyone - art, business, sports, current affairs - Have a look and enjoy!
* You can also try these sites.