Is it still possible to do business on a handshake?

I think there are definitely times when you just need to trust that someone will do what they say they are going to do based on nothing more than a handshake. In the end, however it proves best to back up everything in written form to allow for our posterity to accurately reflect what was agreed or accomplished. Otherwise, risk a "he said, she said" conversation at some later date.
If there ever is a discrepancy this "back-up" will be the meter stick against whcih everything else that transpires will be measured. Try to be brief, accurate and succinct. Everyone will appreciate it.