BrainPop Jr. is in the BrainPop family of websites. It features educational videos on a wide variety of topics, from health to math and literacy. Students love watching the videos, and then it includes followup activities, such as quizzes, games, and even jokes. It requires a subscription for some videos, but others are free.
This simple site is a nice IWB online activity where students can choose letters to spell different words based on objects that they see. I really wish I could embed it, perhaps into an interactive lesson plan, but the little kids K-2, will like it.