Anyone know of any sites that offer free third part add-ins?
If you mean "actual" Add-Ins (as in Tools menu, Add-Ins), I don't believe there are any.
Windows MVP, Messenger
Messenger Resources - http://messenger.jonathankay.com
(From the Netscape web site)
What's New in Version 4.7
1024-bit "KEYGEN" added to export versions
Form signing bug fix related to signing-only certificate
Simplified process for obtaining digital certificates
New 56-bit DES ciphers added to both export and US versions (requires
new SSL cipher suite server-side)
Various bug fixes
10. coding add-ins ?
11. Excel Add-Ins?