There are some nice articles here:

http://www.malesubmission.com/faq/cbt.htm

and

http://www.fetishexchange.org/cbt1.shtml

that may give you some good ideas.

Suggestion:

If you've a vibrating toy in the house, you may want to practice a little orgasm control/denial.

Tie or secure said toy to your erection, turn it on and see what affect it has on you. Wide ribbons and ladies hair bands - without the metal clips - make excellent decorative bonds.

Check out the Personal Photo Thread 2 to see what others have tried.

Reminder:
There is a reason why they are called the family jewels. Loss of air/blood flow to any body part is not recommended for periods lasting longer than minutes. Purple may look very pretty, fantastic even, but you don't want to deprive those precious jewels for too long.