ABCMouse is the new favorite in the Ed Tech world. It is an entire learning environment with lessons and activities designed to prepare little ones (2-5) for school. Users can either pick and choose the activities they want to try, or follow a pre-set path that works its way through a standards-aligned curriculum.
If you have an account, you can log in as a teacher and create student accounts, complete with avatars, ability levels, and pre-set lessons. Students can then log into their own accounts, and have everything set up for them to learn and explore the site. There are dozens of printables, too.
For those of you with younger students just learning the alphabet, colors, numbers, and other basics, this is a fantastic place for interactive practice. It is free for teachers and librarians, and requires a subscription for parents.