BusySync is absolutely spectacular-- I've been running it for over a month to sync with Google Calendar and it *just works*. I was using Spanning Sync for six months prior to that but it has various issues (duplicated events, events refusing to sync) and is incredibly slow at syncing... BusySync is instant and hasn't had *a single issue*. It's got a little checkbox if you want to use https, so it's pretty secure too.

Spanning Sync = awesome support, mediocre product
BusySync = awesome PRODUCT

This is what I want to use it for:

I have a MBP with an external FW800 drive that I prefer to boot off of (read/write speeds are about twice as fast), so I mirror the internal and external drive before shutdown.

When I boot off the internal drive, I don't want Spotlight to search the external (since it is a mirror), and when I boot off the external drive, I don't want Spotlight to search the internal.

Spotless makes it easier for me to turn on/off Spotlight for each drive, but it would be amazing if I could set it to automatically select which drive to enable Spotlight on, depending on the name of the boot drive.

If you know of another way to do this, please let me know.