ReadWriteThink has activities designed from grades K-12. You can sort the activities based on what grade level you are looking for. It has activities such as word sorts, venn diagrams, poetry helpers, and many more literacy activities to be used whole class on an interactive whiteboard or individually.
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.