<p>As above. Usually at work someone else does the database design, and when I do personal projects they're small enough to not really require more than five or six tables, but I'm about to start a personal project that I think will probably require around eleven or twelve tables and I'd like something to help me design it neatly and keep track of it. </p>

MySQL Workbench
, while a little buggy, has been invaluable to me since I discovered it.
Visio
has a good visual database designer, but it can't export the result to a MySQL database and is windows only.
phpMyAdmin
also has a
designer tool
which can be used if you correctly configure the
pma database
.