Deryn Mentock from Something Sublime is offering what looks to be a wonderful online class on creating your own closures and clasps.
Here are a few examples from the class:
Now that I've piqued your interest, you can look here for more details on the class. Seriously, go look now.
Deryn is also hosting a giveway .. a spot in her class for two lucky people. I know I'm crossing my fingers. :)