Here's an ASP.NET version of our classic "Tell a Friend" script.
I've tried to reproduce the functionality of the original as closely as possible.
It non only illustrates sending an email, but also includes some interesting
ASP.NET form validation and even some basic regular expression usage.
With some minor changes this would make a great user control that you could
pop right into your site template and let you use it from any page. If there's
enough demand maybe I'll whip up an alternate version to illustrate.