vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
LibreOffice - Base - Base, database, database frontend, LibreOffice, ODF, Open Standards, SQL, ODBC
Freeplane - Freeplane is a powerful and free software for building mind maps.
My Visual Database - Using My Visual Database, you can create databases for invoicing, inventory, CRM, or any specific purpose.
SuperNotecard - Introducing SuperNotecard. SuperNotecard is an online writing tool that features virtual notecards to help arrange facts or scenes, track details, organize paragraphs, and clarify your composition process.
MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.