Yay! I love Karin the Librarian's challenges. I've participated in two now (her Winter Break Challenge was actually my first ever) and love, love, love it. I like the part where you might win a prize, but (really and truly) I actually love the creativity and experimental nature of the challenges she poses.
So, if you're looking to *randomly* participate in a blogging challenge, this may be a great one to sign up for! What a great way to share blogs and ideas!