The Collected Algorithms (CALGO) is part of a family of publications produced by the ACM. Software associated with papers published in the Transactions on Mathematical Software, as well as other ACM journals are incorporated in CALGO.
HSQLDB is the leading SQL relational database engine written in Java. It has a JDBC driver and supports a rich subset of ANSI-92 SQL (BNF tree format) plus SQL 99 and 2003 enhancements. It offers a small (less than 100k in one version for applets), fast database engine which offers both in-memory and disk-based tables and supports embedded and server modes. Additionally, it includes tools such as a minimal web server, in-memory query and management tools (can be run as applets) and a number of demonstration examples.
Apache Derby, an Apache DB subproject, is an open source relational database implemented entirely in Java.
Formerly known as IBM Cloudscape it is now included in Java 6 as Java DB.