Ranked in these QuestionsQuestion Ranking
Pro Use images rather than just words
Numista helps you catalog your coins with pictures rather than words in spreadsheets. You can catalog the coins you have, how many, their condition, and you can essentially bookmark coins you want.
Pro You can trade coins
You can also set up trades. It's the best search engine for coins and you'll find dozens of new coins to collect just by browsing.
Con Not exactly an app
Numista is a website but you can sign up and bookmark the site to your browser's homepage.