i.Scribe is a cross platform email client, address book, and calendar. It is small, fast, and easy to install. It has multi-language support, and currently includes English, French, Chinese Traditional,Italian, Portuguese, Brazilian Portuguese, Japanese, Vietnamese, Czech, Polish, Spanish, German, Russian, and Dutch translations. It is very expandable via a plugin interface, and uses its own HTML engine (and not IE when run on Windows). It supports POP3, [E]SMTP, MIME, IMAP4, and MAPI. An integrated contact database and calendar are included.
PlexGlobe is a set of tools for travelers and multilingual/multicultural users. It includes a world clock, a world calendar (Gregorian, Japanese, Hebrew, Islamic, Buddhist, etc.), a stop watch, a metric conversion tool, a date calculator, an NTP-based atomic clock, appointments/reminders, people search, sunrise/sunset and moonrise/moonset, prayer timings and adhan for Muslims, country information from the Library of Congress/CIA, weather information, currency conversion, flight times and distances, language translation, and city maps.
MultiSync is a free modular program to synchronize calendars, address books, and other PIM data between programs on your computer and other computers, mobile devices, PDAs or cell phones. Currently MultiSync has plugins for Ximian Evolution, mobile phones (IrMC and SyncML), Opie/Zaurus devices, PocketPC devices, Palm devices, and LDAP directories.
ytnef is a program to decode TNEF streams (winmail.dat). Unlike other similar programs, it can also decode meeting requests and create VCal entries for easy import. It can also create vCard entries from contact cards and vTodo entries from task entries. It also has a Perl script that can be used in procmail recipes to automatically reformat incoming mail appropriately.
iSync is Apple's new device-synchronization software that automatically synchronizes your contact and calendar information between your Mac, your cell phone, your PDA, your iPod, and your Mac OS X Address Book. iSync also resolves synchronization conflicts no matter how many different digital devices you use. It synchronizes your data in both directions and uses the most current information. If you’ve made a number of changes and the change is unclear, iSync will ask you which information to use when you sync.