First of all, go to Applications -> Utilities and make an alias for the Bluetooth File Exchange. Move this alias to the desktop and rename it as 'P800' or similar. I haven't found a better icon than the bluetooth one the File Exchange app comes with, so I left it at that (it would be neat to have a nice P800 picture instead). You can now drag/drop Contacts, SIS, WAV, MP3, JPG, etc. files to this icon and it will automatically open up a list of bluetooth devices. Use the 'favorites' functionality so that your phone is the only one listed and all you have to do is double click on your handset for the file to be sent to the phone.
Secondly, associate the '.sis' file type (P800 application package) with the Bluetooth file exchange application. You do this by finding a .sis file, right click on it, select 'Show Info'. In the dialog which appears, open the 'Open with:' panel, select 'Other...' from the drop down and navigate your way to the Bluetooth File Exchange app in Applications -> Utilities. Then press the button 'Change All...'. Now, when you download SIS files from sites like my-symbian.com, they will automatically get sent to your phone.
These two things mean I no longer have to connect my phone to my PC to deploy apps, assign pictures to contacts or add new contacts. I think I'll continue to use this functionality even after iSync 2.0 gives me calendar/contact synching.
It would be great to be able to suppress the spurious error message Bluetooth File Exchange always pumps out, telling me the phone says it won't be able to accept my file. This simply adds an extra click. And it would be great to browse the phone too, but that seems to be too much to ask right now...
Enjoy!

