Just like it sounds, Funbrain is the go-to site for all kinds of games and activities!
Just a sampling: Math Arcade (math baseball, connect the dots, etc.); Reading (Reading Arcade, Lost Side of Suburbia, Diary of A Wimpy Kid); Fun (Penguin Drop, Mighty Guy, etc.); Playground (Vine Time, Swing Fling, Log Run) + book recommendations, Funbrain Arcade, Moms' & Kids' Playground, more! Whew!