Interactive, online tool in which students can create webs for a variety of reasons such as brainstorming, essay writing, reading comprehension, etc. I just used it to create a 'To-Do' list, can be utilized effectively for a variety of things.
Book Adventure is a FREE reading motivation program for children in grades K-8. Children create their own book lists from over 6,000 recommended titles, take multiple choice quizzes on the books they've read offline, and earn points and prizes for their literary successes.
This site includes many interactive reading games for children to help them build on such skills as phonological and phonemic awareness, phonics, sight words, vocabulary, etc.
This is a fabulous, in-depth, yet student-accessible primer on grammar. I know, it was created by Canadians, but that's okay. I sometimes use their resources when discussing parts of speech and word interactions in class. Our students are increasingly digital; it helps to speak their language.
This website has many many pages of interactive activities and lessons. Students can study story elements, idioms, pronunciations, reading, spelling, play games, all sorts of things. When you have a day with a CoW, or a day in a lab, you can have the students pick a lesson from a list, or you can print out a page and use it as a sponge activity.
This site is a great tool for anybody looking for activities to help teach particular topics. It's divided up by grade, then by subject. I find this particularly useful for those who are extremely interactive.
This website provides various games for younger elementary students. It has math games related to the seasons and contains math related puzzles as well.