For what its worth, I do an inventory each spring (and sometimes another one after the spring/summer trade rush). The inventory includes the complete name of the plant, the pot, the location, where and how I got it, the number of mature plants, the number of offsets (approximate). Some of this information comes from the pot tag. The inventory takes a week or longer to do, but it gets me doing an assessment of each container (I will also keep a comment in the inventory, if appropriate).
I type everything into an Excel spreadsheet for future reference and comparison to last year's inventory. If I'm going to do a trade, I'll extract the relevant columns from the spreadsheet, past into an email or document, then delete duplicates to create a list of what I have. This list is then sent to the trader. I find it helpful to let people know what is in my collection in addition to what I have available as trade, so they can tell what would be duplicates but are not in sufficient qty to trade.
That way, I have a central place to view the collection as a whole.
It's my goal to eventually set up an MS Access database to contain these inventories (the data formats are compatible), so that I can do reporting from each inventory, as well as more complex analysts between annual inventories.
