Among the many kinds of data you might want to sync between Macs is a category I'll refer to as personal data--contacts, calendars, bookmarks, keychains, preference files, and so on. Apple has built synchronization capabilities for this sort of data directly into OS X, in the form of its Sync Services framework; however, taking advantage of Sync Services requires either a US$100-per-year .Mac (soon to be MobileMe) membership or third-party software.
Use .Mac Sync If you're a .Mac member, you can use .Mac Sync, which supports many kinds of data: Address Book contacts; Dashboard widgets; Dock items; iCal calendars; Safari bookmarks; OS X keychains; Mail account settings, rules, signatures, smart mailboxes, and notes; and application preferences. Third-party applications such as Microsoft Entourage, Panic's Transmit, and Bare Bones Software's Yojimbo can use the same underlying mechanism to synchronize their data via .Mac. In most cases, .Mac Sync operates at the level of individual records (such as iCal events or Keychain items); this increases syncing efficiency and reduces the likelihood of conflicts. When you sync your data with .Mac, OS X copies it to or from Apple's servers behind the scenes, rather than directly between Macs, so both computers don't need to be online at the same time (or even be able to communicate directly with each other).
To turn on .Mac Sync, open the .Mac preference pane. If the Account tab does not already show you as logged in, enter your .Mac user name and password. Now click on the Sync tab. Select the Synchronize With .Mac option and choose how often you'd like to sync (or choose Automatically, which syncs either once per hour or more often if OS X detects that information has changed on one of your computers). Click to put a check mark in the check box for each kind of data you want to sync; then click on Sync Now. Repeat this procedure on each Mac you want to sync. (Although the process sounds simple, you may encounter problems when you try synching--see Stay in Sync: Solve .Mac problems for advice.)Setting up .Mac Sync couldn't be easier-just select the types of data you want to synchronize and then choose how often the syncs will occur.
Use SyncTogether If you're not a .Mac member, you can easily sync your personal data with Mark/Space's SyncTogether 1.0.2 (; $50 for up to three Macs). It uses Sync Services, just as .Mac does, but lets one of your Macs function as the server that coordinates syncing among your computers, rather than relying on Apple's servers. Unlike .Mac Sync, SyncTogether doesn't support keychains, and it has a number of other minor limitations. But it allows you to sync data between different users, something .Mac Sync doesn't allow (and at $50, it's a lot less expensive than .Mac's yearly fee, so it may be a better buy if you don't need .Mac's other features).
After installing SyncTogether on each of your Macs, launch it and follow the setup assistant's instructions. You'll be asked to designate one Mac as a server node, so choose one that's likely to be on and available as often as possible. Other Macs in your group will be client nodes. Once you've set each of your Macs as nodes in the same group, you can select types of data to sync (as in .Mac Sync) and a syncing frequency-anywhere from every 15 minutes to weekly (you can also choose manual syncing).
After the initial setup, SyncTogether provides almost the same day-to-day experience as .Mac Sync for Macs on the same local network, though it's considerably more complicated to synchronize with remote Macs, as this requires either a VPN (virtual private network) connection or knowledge of the remote Mac's IP address.
This story, "Sync Your Personal Data" was originally published by Macworld.