Nothing's more important to your productivity arsenal than a solid scheduling tool, and considering so much of what we do happens at the computer, a good calendar application is just the thing to bring order to your agenda. Keep reading for a detailed look at the top five from our readers. Photo by adamjinj.
Rainlendar (All Platforms)
Rainlendar is an efficient calendar and to-do list app that lives embedded on your desktop. It's completely customisable, and it integrates with virtually any other popular calendar application (meaning that if you don't want to use it independently, you can still install it to embed your favourite calendar on your desktop). Rainlendar's free version sports nearly full functionality, but if you want shared calendar, Outlook, or Google Calendar support (for editing GCal whether you're online or not), you'll need to pony up 10 Euros for a licence.
Google Calendar (Web-based)
Ever since it launched in April of 2006, Google Calendar has quickly built a reputation as the premier web-based calendar. GCal owes much of its popularity to its anywhere accessibility and for bringing the look and feel of a desktop calendar into the web browser. It's fast, it's reliable, and it's continually improving. Even better: GCal can sync with virtually any desktop calendar.
Thunderbird with Lightning (All Platforms)
Combine Mozilla's email application Thunderbird with the Lightning calendar extension and the popular open-source email client instantly becomes a robust calendaring tool. Lightning is relatively young, so it doesn't yet support full integration with your email and contacts like Outlook (luckily those features are on the Lightning roadmap). However, for a free, cross-platform calendar app, you can't find much better than Thunderbird with Lightning. If you'd prefer a standalone calendar to email-plus-calendar, be sure to check out Sunbird, which is basically Lightning as an independent app.
Microsoft Outlook (Windows)
Microsoft Outlook is the de facto calendar and email application of most of the corporate world, which leads many to the "it's only popular because Microsoft forces it down everyone's throats" conclusion. However, with Exchange server support, email integration, Windows Mobile syncing, and great collaboration tools, Microsoft Outlook really earns its place as a killer desktop calendar. The biggest drawback: Outlook comes with a hefty price tag.
iCal (Mac OS X)
iCal comes standard with Mac OS X, and this simple but increasingly powerful calendar application proves to be all many Mac users ever need. iCal integrates smoothly with the rest of the your Mac apps, supports MobileMe syncing to the cloud (as long as MobileMe is working, that is), and the iPhone/iPod touch version of iCal puts your entire schedule conveniently in your pocket.
A Note on Synchronisation
I turns out that tons of you actually use more than one calendar application in order to sync your schedule between your desktop and the web. For most, that means syncing one desktop application—like Outlook, iCal, or Thunderbird/Sunbird—with Google Calendar. If you're using one of those desktop solutions and syncing sounds appealing, check out our guide to syncing any desktop calendar with Google Calendar.
Whether or not we mentioned it, let's hear more about the virtues of your favourite calendar app in the comments.