Apache CouchDB is a free and open source document-oriented DBMS which can be queried through the standard REST operations (those of HTTP). Instead of relying on a set of tables with a fixed structure, it uses the documents as storage units. These documents are natively served as JSON key-value pairs, in a fully web style.
CouchDB is specialized for hadling very large databases which can be natively distributed and replicated over several servers. Its RESTful API allows to query the databases from all languages, and even from a simple web browser, or a command line. This tutorial from IBM explains how to query CouchDB from PHP, employing a object-oriented wrapper.
MySQL is nowadays a standard in the field of databases for the Web. But what are the best tools for MySQL database management?
If you are looking for an alternative to PHPMyAdmin or MySQL GUI Tools here is a review of 10 graphical tools, either free or commercial.