I maintain a spreadsheet with descriptions, date acquired, provenance, price paid, etc. etc. as well as well as a photo imbedded on each one. I keep it with my important documents.
I figure I am not going to live forever and with my idiot kids (well, idiots in their knowledge of pipes...), they would just stick them on a yard sale table for 5 bucks each and inevitably someone on here would be starting a thread about how they got an Ivarsson or Knudsen or Bang or etc. etc. for just 5 bucks at a garage sale put on by a bunch of idiot kids....