This is also a good place to look up some min/max info on different data types. See: http://blogs.techrepublic.com.com/10things/?p=355

If you use SQL when testing, and you'd like to see how your application works when the database is working hard without much effort, try a CROSS JOIN (also known as a Cartesian product) statement on two large tables. This SQL statement will produce a combination of all the rows in two or more tables, and can really make a database work hard. Be sure to monitor your database to see what effect this has on processing. If it starts to really thrash, try out your web or other application to see how it behaves when the database is under load.

Caution: only do this on a system where you have the ability to do what you like to the database, others aren't depending on it, and you can kill your SQL process if it gets out of control.

MySQL Workbench is an ERD tool for MySQL. It's not ERWIN but it's a decent tool.