Tools: Organizing Physical Stuff

CamCard (free)
Scan, manage, sync and exchange business cards. Android, iOS, web.

CamScanner (free and paid options)
Scan documents with your phone; creates OCR; image editing; customizable watermark; easy to share documents. Android and iOS.

Discogs (free)
Track and organize your CDs, records, and cassettes. Includes a marketplace to sell, trade, and buy items. Web.

Encircle (free)
Quickly and accurately document the contents within your home. Android and iOS.

LibraryThing (free and paid options)
Track and organize your media: books, zines, CDs, records, DVDs, and much more. Web-based, but has apps.

Memento (paid options)
Track and organize anything with the extremely customizable database for Android & Desktop.

Sortly (free and paid options)
A simple yet powerful way to accurately document everything you have at home, in storage, or across multiple properties. Web, Android, iOS.