Attention teenagers and overzealous social networkers with an predilection for giving strangers your phone number (despite your mother’s and my best advice):

If you’ve ever met someone who you’d like to start talking to on the phone but don’t want to give him/her your real number, in the unlikely event that s/he turns out to be mental, check out Jangl.  Jangl is a privacy insurance policy for people like you.  It gives users a way of getting in touch with others over the phone without swapping numbers.  Here’s how it works:

A) Go to Jangl.com
B) Make up a “Jangl ID” (like a screen name) and register it (along with your phone number) on Jangl.com.
C) The next time you meet someone you want to talk with over the phone but don’t know well enough to give your number, give him/her your Jangl ID.
D) When S/he registers on Jangl.com, you both get a proxy phone number on which to contact each other.  That proxy number re-directs calls from either of you to the other.
E) Neither party’s real digits are ever revealed, and either of you can turn off the number at any time.

I’ve not yet tried it, but then again, I don’t go giving my phone number out to people I don’t know (at least enough to guess that they’re not crazy).  That said, I can see how this “service” would be useful if you’re less discriminating about who gets your digits – especially in the US where people get charged for incoming mobile phone calls.