Address Book

• Using Bluetooth for SMS (deprecated in Leopard, which removed all traces of this feature)
• Connecting to Exchange using iSync (also deprecated, kept for reference)

• Address Book Sync for syncing with Facebook (inc. photos)
• Address-o-Sync
• Address-O-Matic
• Whereabouts

Connecting to Exchange (Leopard) and Active Directory via LDAP

The only real problem is figuring out the correct naming context¹, which can be done by issuing:

$ ldapsearch -h your.exchange.server -x -b '' -s base '(objectclass=*)' 'namingContexts'

…and pick out the correct namingContext entry from the output. Bear in mind that on a multi-branch tree (like the ones in multinationals) you might not want to pick the shortest.

This AppleScript (taken from here) is very useful when keeping track of modifications done by syncing your address book with other sources:

defaults write com.apple.AddressBook ABShowDebugMenu -bool true

¹ Abridged from here for my own reference.