"Quizzes, tests, exercises and puzzles to help you learn English as a Second Language (ESL). This project of The Internet TESL Journal (iteslj.org) has thousands of contributions by many teachers." This site offers quizzes and crosswords for students learning English as well as bilinbual quizzes that take the students first language into account. It has a pretty large bilingual quiz base that uses many of the worlds languages from Zulu to Spanish to Arabic. It seems to be a little childish looking and there aren't a ton of quizzes to choose from but it could definitely be a good resource for extra practice for students.
Sorry, this resource isn't free, but if your ESL program decides they can spare just $5-6/week, then both students and teachers can use the same password to access news stories as well as features such as audio recordings of stories, exercises, crossword puzzles, and definitions of key vocabulary. I taught a weekly current events ESL class for adults, and students loved News For You. Each week there are 7 new stories, and several students would read/listen to all the stories before coming to class. I would pick one or two stories to focus on during the 90-minute class. I made my own activities, but students who wanted to could do the online exercises at a library or community center computer. However, because the stories are written for adults who are learning to read (either ABE or ESL students), the content is not as authentic as a regular newspaper. But the fact that it is motivating and accessible to students and encourages lively discussions in class makes it a nice resource.
The New York Times has a blog named 'The Learning Network'. They post several activities everyday. These include cloze texts, multiple choice reading comprehension questions, puzzles and videos with discussion questions.
They also have a word-of-the-day page where they post a new word everyday with its meaning and a sample sentence.
I check their page from time to time to see if any of the activities would be appropriate for my students. You can also assign them as homework or students can work on them on their own.