One material generator that I often use is EdHelper especially for reading instruction. Since I use a lot of chapter books for whole class books, literature bookclubs, and independent reading, I use Ed Helper to access already created vocabulary word lists and reading quizzes for specific books. I also use it for ideas for end of book activities and projects.
Superteacherworksheets is another website that I use frequently especially for math instruction. It's format is easy to use and it's free. Whenever I need extra practice worksheets for specific skills or even homework sheets, I use this worksheet generator.
Acccelerated Math by the Renaissance Learning program is a math curriculum generator that I use every week. I assign students a practice sheet on Monday, and they turn it in by Thursday. The answers to these practice sheets are put on scan tron cards which I put through a scanner. If they are struggling on a specific skill, the program alerts me. If they are mastering specific skills, I can assign them a test to take. It is basic skill drill type curriculum, but I've found that it provides much needed practice for my students.