Oz, you're sick and I can't thank you enough for being sicker than me ;-). I've toyed with pressure points and pin pricks in public. Pin pricks are very effective and can be executed very stealthily especially with a safety pin or straight pin.

I have found that I enjoy playing with remote controlled vibrators much more. I have one that gives me about 30 feet and is whisper quiet. Probably my favorite toy, because nothing beats having her ordering food or speaking to a salesperson and suddenly stuck speechless by my hidden friend.