not crochet, but a great idea if you are crafty~! Animal bookends.

[Knit Happens]

this is a free knit pattern from Lion Brand...I think it is absolute GENIUS idea .... cover up those bland standard office issue metal bookends with an animal---if you've got a bit of designer inside you, you can let your imagination soar. Even tho this pattern is knit, the crochet ideas are already running through my mind! If you can't access the pattern, you need to become a Lion Brand site free member to access all of their patterns. http://www.lionbrand.com/patterns/80357AD.html?noImages=

[everkutz]

I love this idea! This could easily be done in crochet or with felt. Thanks for sharing!

[Granny Square]

Aside from the tail, those are very simple shapes, and the tail isn't that big of a deal. I bet you could make much cuter ones in crochet. Great idea!