Finally, a tech product that is useful.

“Mail Goggles” is dubbed as a breathalyzer for your email.  This Gmail add-on makes it harder to send email when you are, um, not thinking clearly, by asking a series of math problems during the times you specify.  If you get any of the questions wrong, Mail Goggles will say, “Water and bed for you. Or try again.” 

You can enable this tool for your Gmail for free from Google Labs.