L.
When my daughter turned two I made her the blues clues cakes off of this website:
http://www.dltk-kids.com/Crafts/cartoons/bluecake/index.htm
I don't really bake much but it was worth it!
I made both the doggy pawprint cake and the cake of Blue.
I didn't have many kids at this party or I think I would have maybe done a Blues Clues scavenger hunt. You could draw pictures in little notebooks of the things the kids need to find or put little paw prints on them? Maybe let them make sock puppets like they do in several of the episodes. Hope this gives you a few starter ideas anyway.
Good luck and have fun!
L.