Database

H2

http://www.h2database.com/

HSQLDB

http://hsqldb.org/

McKoi

http://mckoi.com/database/

Firebird

http://www.firebirdsql.org/

PostgreSQL

http://www.postgresql.org/

DB Solo

http://www.dbsolo.com/

Execute Query

http://executequery.org/

Aqua Data Studio

http://www.aquafold.com/

SquirreL SQL

http://www.squirrelsql.org/

SQL Developer

http://sqldeveloper.solyp.com/index.html

TOra

http://tora.sourceforge.net/