But while I'm thinking about this, I actually have a spreadsheet as a Google document that I can access from any computer or my phone. On it is a matrix listing every bike I have (including unbuilt framesets), their serial number, and all their build details. I mean everything. Down to color of bar tape, tire size, and importantly, a photo of each bike in what is recognizably my living room. This is really so i can keep track of what I'm doing with bikes, but it would also be evidence in case something was ever stolen. I even have a record of who I bought the bike or frame from, including email address / phone number, in case I need backup! It was easy to do and I recommend it to everyone.