Glom is a GUI that allows you to design MySQL table definitions and the relationships between them. It also allows you to edit and search the data in those tables.
KSqlAnalyzer is a tool for easy accessing the data of a MS-SQL-Database. The functionality and the look&feel are similar to the program 'SQL-Query-Analyzer' written by Microsoft.
SafeSQL is an SQL query processer to automate the tedious tasks of syntax testing, injection attack-proofing, dropping parts of queries and other misc features.