<p>I want to reverse engineer (import into diagram form) the database definition dump of a database I have, then since no foreign keys are defined in this particular database, I want to be able to manually create the table to table key mappings (using crow feet notation if possible).</p>

<p>I've taken a look at MySQL Workbench, and it gets me 85% of the way there.
The nice little relationship lines won't show up though, and the auto arrange is horrible. A quick search of google turns up several other options, so I <em>can</em> evaluate these on my own, but:</p>

<p>Can I get some feedback from you guys for which are your favorite tools to use for this scenario? Why do you like that(your) particular tool?</p>

<p>My intended purpose is to take a legacy database, and train jr. engineers on the organization of the DB. Visual aids are nifty. My fallback option is to recreate an ER diagram by hand. Not fun for 250+ tables. </p>

I've had some success using two commercial (but relatively cheap!) tools- but I still haven't found any really solid open source ones after months of looking.
MyEclipseIDE
is a subscription product, I think it's around $60 a year. It's a set of bundled plugins for Eclipse, one of them is an ERD analyzer that works OK. If you're programming in Java (or another eclipse-supported language), it may be worth it.
SQLMaestro for MySQL
: This one is a bit more expensive, with a $99 noncommercial / $179 single seat license. The ERD it generates is much better, and it provides other tools that make it easier to administer and maintain a more complex schema.
My understanding is that MySQL Workbench is still under active development, but they've been banging on it for a long time without really wrapping it up. Maybe now that Sun owns them, they'll get it together.