icalBuddy is a command-line utility that can be used to get lists of items (i.e. events and tasks/todos) from the OS X calendar database.
A Ruby script that will read your iPhone's call log and copy the calls into an iCal calendar.
More RSS / Blogs to iCal
Another RSS to iCal converter. Uses magpieRSS.
RSS to iCal converter. Includes a built in RSS parser.