General
ADSI SDK (includes Compiled Help file, ADSVW and adssecurity.dll)
ADSVW INI file set up for LDAP communication to an Exchange server (place in your Windows root directory, eg. c:\Winnt - or - C:\Windows)
Exchange 2000 post-SP3 hotfix allows programattic access to SMTP Virtual server Routing and access lists

Outlook
HOWTO: ALlow downloading of attachments in Outlook versions
Outlook 2002 and Programmatic access to MAPI subsystem
Outlook Administrative Package Download site (98/NT4/W2K/ME)

Perl
Exchange 2000, 2003 Rule management ASP website (originally a MSDN sample -- with modifications) -- includes rulesasp.dll as well
Perl Script for Exchange (and Outlook) 5.5, 2000, 2003 Rule Creation (Helpful sor SPAM processing)