GCALDaemon is an OS-independent Java program that offers two-way synchronization between Google Calendar and various iCalendar compatible calendar applications. GCALDaemon is primarily designed as a calendar synchronizer but it can also be used as a Gmail notifier, Address Book importer, Gmail terminal and RSS feed converter.
Features
1. Open source and completely free of charge
2. OS-independent standalone application (Java 1.5)
3. Bidirectional sync between iCalendar and Google Calendar
4. View and edit your Google Calendar offline
5. Supports 'Google Apps for Your Domain'
6. Supports multiple file listeners with multiple Google Accounts
7. Makes Gmail contacts accessible via LDAP
8. Customizable Gmail notification
9. Converts RSS/ATOM feed to iCalendar format
10. Reusable mail transfer agent
11. Remote control your computer via Gmail
12. Multi-user abilities (up to 30-40 HTTP and LDAP clients)
13. Run in service mode on Windows NT/2000/XP
14. Run in embedded mode in a Servlet Container
15. Low memory usage (10-20 MBytes)
16. Automatic and fast (3-5 sec/sync)
17. Customizable logging system (Log4J / CommonsLogging)
18. Ability to do TCP/IP hostname/address filtering