Since two months I'm using Google Calendar, and I've been looking around for a nice way to synchronize my online calendar with my mobile phone. This is a fairly simple device, a Sony Ericsson C902. It's just a Java enabled phone with a simple built-in calendar tool, nothing special. I have tried different solutions, but it was a bit tough to get it right.

These were the solutions I have tried, the last one is the most satisfactory solution which I'm using at this moment.

• At first, I tried Google's mobile web interface for Google Calendar. You only need a browser for that, which is often built-in. Of course, when you have Java ME, you should use Opera Mini anyway. While this shows your events quite nicely, there's a major problem: it's read-only. I have seen screenshots where you have the ability to add new events, but that edit box at the bottom of the page just shows up as a horizontal line; unusable. And events cannot be edited. Pretty worthless.
• The next solution I tried was GCalSync. This Java ME application actually uses the device's built-in calendar and connects with Google and syncs your data. At first glance, it seems to work quite nicely. But soon I found out that events were missing at my phone's side. The problem: it cannot deal with repeating events. Not as worthless as the previous solution, but still worthless.
• Time for the next one, another Java ME application. It's Gcal. Don't be scared away by the butt-ugly website, the application doesn't look that bad. You fill in your Google credentials and shows the calendar in its own interface. You can see the daily view and a month view. It is possible to add events, but there was no way to edit an event. Incredible. Just what I didn't need. Also, because all operations are online, it's a bit slow in usage. Although I seem to remember that a future release would support editing, it was no motivation for me to stick with this application.
• My final and best solution was using GooSync. GooSync is an online service, which synchronizes Google Calendar with your built-in calendar. There's no crappy Java ME application involved, the synchronization part is actually built-in. Downside: it's not free. It used to be free up to mid October 2009, now you can take a GooSync Lite account for 5.99 pounds/year. Because I was satisfied with the service when I used the free service, I thought it was worth the money.
  Here's how it works:
  You create an account at GooSync and add your phone there.
  On my C902, under the Organizer menu item, there's an item called Synchronization. Create a new synchronization entry and fill in your GooSync account credentials (server: http://sync2.goosync.com). The calendar is just called calendar. At the last tab, you can choose the synchronization interval, ranging from once an hour to seven days. When this is complete, your phone will synchronize your calendar in the background. Non-obtrusive and it properly takes care of repeating events, locations, reminders and timezones. You can safely use your phone's built-in calendar, after some time you'll see your changes appear online as well. So while it's not free, I think it's the best solution out there.
  GooSync also supports synchronizing your tasks and contacts, but I cannot tell anything about that.