Data quality analysis, profiling, cleansing, duplicate detection +more
DataCleaner is a data quality analysis application and a solution platform for DQ solutions. It's core is a strong data profiling engine, which is extensible and thereby adds data cleansing, transformations, enrichment, deduplication, matching and merging.
Website: http://datacleaner.github.io
Sedna is a native full-featured XML database management system.
Sedna is a free native XML database which provides a full range of core database services - persistent storage, ACID transactions, security, indices, hot backup. Flexible XML processing facilities include W3C XQuery implementation, tight integration of XQuery with full-text search facilities and a node-level update language.
LEAP is an RDBMS (Relational Database Management System) implementing the relational Algebra - a core part of relational database theory. It is primarily used as an educational tool, but has found some novel uses and applications.