My Dad collects US silver coins, mostly American Silver Eagles, so I built him CoinVault, a coin collection tracker that runs on his own computer and keeps everything there.
It shows what the collection is worth from the current silver and gold prices, charts the value over time, and shows which coins are missing from a set. He can add his own front and back photos, and it makes a daily backup. The text is big and the words are plain. A Sell button drafts an eBay listing to copy; nothing is posted for him.