Mac OS X Server's adaptive firewall (afctl) does a good job of catching brute-force login attacks on most services, but it doesn't catch PPTP attacks. The script below checks the system log for such attacks, and then uses afctl to block offending hosts for a week (you can, of course, change the parameters if you wish).
This may work on Leopard Server as well, but I haven't tested it. There are several brute-force VPN protocol attacks rampant on the internet, and they may leave your VPN service in an unusable state by flooding it with connection requests.
Tiger includes a nicely-integrated Jabber server, but for those of us who have not yet upgraded, here's the trick to getting jabberd running on Panther.
After upgrading my home system to Tiger, I noticed that my RsyncX backups to an external FireWire drive were no longer working. Much consternation and hair-pulling later, I realized that the Spotlight indexing was causing problems with RsyncX.
Thursby's ADmitMac is a full-featured SMB/CIFS client that contains a lot of great features to hook Mac OS X into an Active Directory infrastructure. Be aware, though, that there is a downside involved. Thursby chose to implement a different method of handling resource forks on non-AFP filesystems than Apple uses in its samba-based SMB client.
Get Windows to play nice with your OS X clients using NFS AD integration works reasonably well for Mac OS X clients, but what if you're running, say, an XServe G5, and you need to provide access to Windows-based home directories for multiple command-line users (via ssh, telnet, etc.
For those of us who either don't want to use sieve, or haven't been able to make it work properly--despite Mr. Rennich's best efforts to help--setting up procmail filtering is not too difficult.
