The most unconventional online calendar that I'm going to recommend for online calendar newbies is 30Boxes. 30Boxes is a new calendar that focuses on using tagging to help you manage your appointments. It uses a month view on log-in (no week view) with a pop-up day view when you click on a day, but allows flexible searching and tagging. 30Boxes also has a quick entry box that lets you type in your appointment and hit enter and watch it appear without fiddling around with buttons or forms. Once you master it it's quite convenient. 30Boxes also offers a to-do list that uses only tags, which is very slick.

30Boxes allows you to view friends' calendars, and also allows you to subscribe to your calendar via RSS feeds, or using an iCal standard feed. Getting used to the tags and the month-only view can be a bit odd, but it's a fast and nimble online calendar. One final feature that's super useful is that 30Boxes has a mobile version that's slimmed down so you can view it on a PDA with web access. You can have events e-mailed, or even text messaged to you on your phone so you don't miss important events.

30Boxes' ability to add a calendar to your website with a piece of code was fairly easy. Just click on the 'share' chicklet in the upper left, and select 'share by tags' in the drop-down list. From there you can put the shared calendar of your choice on your website or blog.

Google calendar is fast becoming a well-adopted calendar by many. What I like about Google calendar is that it is easy to access if you're already using Google mail. Even if you're not, it's a very solid internet calendar. You can drag your appointments around with the mouse, create one using a fast entry box -- just like with 30Boxes -- and you can create multiple calendars for the different kinds of events you have.

Google's calendars can be shared with others that you invite via email, or you can make a calendar fully public. Right now the one big downside to Google calendar is that it doesn't have a mobile view option. However it does have text messaging or email for alerts, which is a bit of a workaround. Google has more views than 30Boxes, including week, day, agenda, and a custom view you can set up however you wish. You can add Google calendars to your website or blog.

Where Google's calendar shines is its API (a way of letting outside applications hook into the calendar's information). Google has a number of applications that sit on your desktop and work with the calendar. Spanning Sync for the Macintosh lets you sync your iCal calendars back and forth with Google calendar. Calgoo is a java-based calendar application that runs on Windows, Mac, or Linux that takes your Google calendar and lets you view it offline and sync your calendar back and forth.

And last, but not least, is Yahoo!'s calendar. Yahoo! has had a web based calendar as part of its free e-mail and web applications process for many years now. Adding and updating events with Yahoo! calendar is a bit of a chore that involves using forms, no quick add, no drag and dropping of events. However Yahoo! does allow sharing, and for Windows users, Yahoo! allows a pretty nifty sync via Intellisync that will get your Yahoo! calendar, address-book, and notes to sync with Outlook, Palm, or your PDA. Just click on 'Sync' in the upper right-hand corner to get started with downloading the software. With this set-up on Windows you can make changes in Outlook or on your PDA and see them uploaded, or vice versa. There is also a Google calendar gadget you can have on your Google desktop.

There are more solutions out there, but with many readers already using Yahoo! mail or Google mail, it makes sense to try out the calendars already available to you so as not to add another service you have to keep track of.

Some faster summaries of other calendars out there:

Airset is a calendar online that is very fully featured (including allowing you to bring-in group management and calendars). Airset features mobile syncing, allowing you to use your mobile device to access it, which is very compelling, and it also synchronizes with your Outlook or Palm.

Planzo.com offers a variety of synchronizing, but sends out emails to contacts to get them to update their info, which could be annoying, though many swear by the utility of Planzo. Similarly named Plaxo is another well-featured calendar to look into, offering all sorts of synchronizing and mobile access across many different computing environments and a free online version. CalendarHub is another online calendar to be checked out that features many of the above abilities mentioned, though without the syncing it has a number of import/export options.

In the end, a calendar is a personal preference, but playing around and trying these will give you a solid idea of what's out there. What do you use for your online calendar? I'm always interested to try new ones out.

Tobias Buckell is an author, freelance writer and professional blogger.