phpDays is a flexible PHP 5 framework for rapid Web site development. It features an MVC architecture, Ajax support, YAML configuration, database abstraction (MySQL, PostgreSQL, MS SQL, etc.), a good collection of standard models, an excellent quick start guide, and logging to files or firephp.
Squarebase is a Web-based interface for MySQL databases. The basic idea is that it builds a database (called the "metabase") that describes the structure of the database. The information in the metabase is used to format lists and forms for browsing and editing the contents of the database.
phpLiteAdmin is a Web-based database admin tool with support for SQLite 2 and 3. It consists of a single 60KB source file that can simply be dropped into a directory on your server and then visited in a browser. There is virtually no setup required except for specifying your database(s). The available operations, feature set, interface, and user experience is comparable to phpMyAdmin for MySQL.