Interactive Learning Sites for Education
This website has links to a huge collection of online flash games for learning English. The games are hosted on a variety of other websites. Some of the links are either broken or the content no longer available which is a shame. Hopefully the website owner will soon update these links.
The sections to choose from include grammar, punctuation, compound words, sentences, spelling etc. Some of the content is targeted at kids, but there is enough for most adult learners busy. The writing section has a few useful games as does the parts of speech section.
I would also recommend going to the front page of the website at http://interactivesites.weebly.com/ to see the impressive collection of flash games on other topics such as math, science, art and others. There is even a section with links to flash games to practice your typing skills.