SQL Yog

A very good tool. Works for MySQL.

Here is a list of free downloads:

http://code.google.com/p/sqlyog/downloads/list

(don't try to download it from their site since it's not free anymore, these copies are the ones they used to give as freeware).

DB2 Survival Guide

This is a very good reference page for those who are trying to learn DB2.

http://www.michael-thomas.com/tech/db2/db2_survival_guide.htm