You can connect to your phone via Infrared (IrDA), Serial, Bluetooth and USB (which appears as a virtual serial interface).

After you get your phone connected you can:

• Transfer files (photos, ringtones, themes, etc.) from and to your device
• Synchronize you address book with FMA’s internal address book or with Microsoft Outlook. Add, remove or edit contacts.
• Manage your missed, placed and received calls, etc.
• Write, send and receive SMS messages on the computer (believe me it is much easier to type)
• Various cool statistics like battery temperature, power consumption, serial numbers and software versions, etc.
• Has a scripting framework, which can attach to various events to customize the program behavior in certain situations.
• You can also make calls from your computer, but this feature requires some bluetooth software and I have connected via USB cable, so I have not tried it.

And more…One very nice feature I would much like to try is controlling your PC through the phone via a bluetooth connection. This is a perfect tool for presentations – instead of carrying a wireless presenter you can control the presentation with your phone, and since most new laptops nowadays have a Bluetooth connectivity should be very easy. How cool is that, huh? You will make an impression!

Overall I love the program and use it with my W810i.

Update: Apparently many of the Sony Ericsson phones have the Bluetooth remote control feature out of the box and FMA provides additional profiles and customization. Here is an article about the feature and a profile editor.