[penguinhead]

Can anyone recommend a script that I can use to allow visitors to my site to refer it to their friends.

The only thing is, I am looking for a script that enables me to view how many times a particular email has recomended the site to valid email addresses! Hence the program would need to check if the emails were valid and if any emails sent bounced!

[Highlander]

I use Apply Refer Pro 2.3. It is a very good script with a lot of statistics. It has the following features and statistics:

Total Number of Senders:
Total Number of Receivers:
Average number of e-mail addresses referred:
Next Generation Referrals:
Next Generation Viral Rate:
View Senders
View Receivers
Export E-Mails
View Referred URL's
Configure
Test it
Get Plug-In Code
Delete Data



For checking bounced emails you could set your email address in the admin section as refer@yoursite.com. This would help you to identify any bounces from the referer proogram. There is a free version with fewer features and the full pro version for $29 with all the statisics. Here is their website.

http://www.applytools.com/applyRefer.html