Blue's Clues Printables: Features more than 50 print-and-play activities, coloring pages, and greeting cards. From NickJr.com.
Callie's Blues Clues: A fan site by a four-year-old named Callie, with pictures, coloring pages to print, games, and music.
DLTK-Kids.com: Blue's Clues: Free printable template for crafts. Also includes coloring pages, games, and printable cards.