iSynCal is built to synchronize Events and todo from iCal calendars between two or more Mac computers using the standard Apple File Sharing shipped with Mac OSX. Using iSynCal, you no longer need a .Mac account neither to publish your calendars on an external FTP or WebDav server.
You can even use iSynCal to sync your iCal calendars with your iPod or between multiple users on the same Mac.
Since iSynCal reads and synchronizes calendar files based on the open iCalendar standard, used by iCal and by many similar multiplatform applications, it's also possible to use it to sync a Mac user's iCal calendars with those generated, for example, by Mozilla Sunbird or the Calendar extension for Firefox and Thunderbird.
It's even possible to schedule the synchronizations and run them in unattended mode.
