Basically two thing. First would be some Cloud based solution that can work across all three platforms. Awhile back Dropbox could do this, but they dropped their cloud sync support. Which really sucks as we were using it with a couple of our other apps and were planning on doing it with TM. However right now we don't know of any free cloud based providers that can do syncing. The second thing is time, which I do not have these days. We are currently working on several very long term projects. At the moment, we are only fixing critical bugs. For example when things break due to new OS updates.