SQL Fiddle is a tool for database developers to test out their SQL queries.

South brings migrations to Django applications. Its main objectives are to provide a simple, stable and database-independent migration layer to prevent all the hassle schema changes over time bring to your Django applications.

Chive is a next generation MySQL database management tool. The web-based user interface supports most of the common operations needed by software developers and database admins (databases, tables, indices, keys, triggers, views, routines, privileges management, import/export).

SQL diagnostic manager is a powerful performance monitoring and diagnostics solution that proactively alerts administrators to health, performance or availability problems within their SQL Server environment, all from a central console.

SQLscaler simulates production workloads in a test environment and providing in-depth analysis of test results so you can spot problems before going into production.

Lets you query activerecord using ruby code. Translates it to SQL.

Junebug is a well designed, clean and simple wiki developed on whytheluckystiff's Camping framework

Search through publicly available source code using Google.