Gynzy is a very cool website with lots of activities for elementary teachers to use with interactive whiteboards, interactive projectors or slates. Start by creating a free account. Once you're logged in, search for activities by keyword or click a subject area icon to view all available activities for that subject. Once you've selected a subject, you can narrow the search by grade level or topic.
If you like a particular activity, use the star button in the bottom corner to add it as a favorite.
Favorites will appear on the Favorites tab on the left hand side for easy access.