A piano-roll graph where each horizontal increment is a day and for each bar shown vertically in the database has a dot showing its presence or a gap when not there. Would make it visually easy to see bars dipping in/out of the pool. Perhaps filter out bars which don't move to reduce clutter.

correlate increases in the SLV inventory with drawdowns of the COMEX registered inventory over the past several years. (originally suggested by Xaritas)

Do a Google Maps implementation to show the geographical ETF vault locations (as a permanent feature)

If a bar has been identified as being in the inventory previously, it should have an 'age' identifier. Requires historical lists to be complete.