I haven't actually used any of these; just thought I'd try them out some time when I got one of those famous round tuits... They're mostly links found from [link|http://www.torry.net/|Torry's], so don't be too surprised if most everything is for Windows. (And written in Delphi! :-)
First of all, [link|http://www.casestudio.com/enu/|CHARONWARE] says that "with CASE Studio 2, you will create large Entity relationship diagrams for numerous databases in minutes! This data modeling tool is an ideal choice for companies and developers who want to work with their own databases comfortably." -- it has ERD's, Reverse Engineering, "Graphic editing of the Data Flow diagrams" (?), etc, etc.
$325 Full, $163 Lite versions (additional licenses after the first are less than a third of those prices).
Second, [link|http://www.datanamic.com/|Datanamic] makes "DeZign for databases", which they say is "a database development tool using an entity relationship diagram. It visually supports the lay out of the entities and relationships and automatically generates SQL schemas for most leading databases." Seems to have most functions you'd want: ERD editor, schema generation, "Powerful" report generator, and so on and on.
$149, or you can download a free evaluation version.
A long shot: [link|http://cs.joensuu.fi/~lrauti/|Lasse Rautiainen] of Joensuu University has an "Oracle Database Documentation" thingy available for download; maybe that does ERDs too?
The rest of these products don't (as far as I know) do DB modeling, ER diagramming and all that shit, per se... But what the hey, I'm including them anyway, just in case. :-)
To begin with, of course, Sweden's contribution: [link|http://www.globecom.se/tora/|TOra Toolkit for Oracle] -- "a cross platform toolkit for Oracle which aims to help the DBA or developer of database application. Currently binaries are available for Linux and Windows, but it is known to compile on Solaris and probably works on other unixes. It features an SQL worksheet with PL/SQL block parsing, PL/SQL debugger and editor with syntax highlighting and code completion and a full suite of DBA management tools." It also has explain-plan, statistics, schema browser, blablah, breakpoints, watches, yaddaydda, in the PL/SQL debugger, server tuning / overview, tuning charts, security manager, storage manager, session manager, "Database & schema comparison and server" (?), yaddaydda, blablah... LOTS of features!
Somewhat ambiguously, it says: "If you are using this program in your work on Windows you need to purchase a commercial license." First nine licenses $100 apiece; drops succesively to $50 per head in lots of 100+ ... But, does this mean, if you use it commercially -- "in your work" -- on platforms *other* than Windows, it's free (as in beer)?
I think it does.
[link|http://www.allroundautomations.com/|Allround Automations] claims to be "a leading provider of Oracle development tools". Their PL/SQL Developer product is, they say, "an Integrated Development Environment for developing, testing, debugging and optimizing Oracle PL/SQL stored program units", and features an integrated debugger, a graphical Query Builder, a configurable tree-view Object Browser, yadda yadda yadda.
Single license US $150, annual service contract another $50, 30-day trial version free for the download.
If you aren't afraid of Russians, go to [link|http://www.dbwork.kuban.ru/|Degisy Software Corporation]. Their Database Workshop seems interesting, though the English-language section of their Web site seems to be a bit out of date -- the date of 20 February, 2002, doesn't inspire much confidence in me, at least -- but over on the Russian side, it's been updated fairly regularly and recently, so the product shouldn't be totally defunct, at least.
And if you want to try reading Portuguese in stead of Russian, go to [link|http://www.dbmaster.com.br/|Db Master Sistemas LTDA] in Brazil. The [link|http://www.dbmaster.com.br/dbmanager_eng.html|English page] for their DbManager product doesn't seem to want to load except as part of their frame set, but click the "Produtos" link over on the left and you'll get to it.
Even further afield (from your original question), [link|http://www.crlab.com/|Core Lab]'s OraTools is "a simple to use program to manipulate data and database objects of Oracle RDBMS. It is useful for developers to execute, test and debug SQL and PL/SQL statements and for database administrators to navigate, create and modify database objects and schemas." They also have an Oracle Class Library, which I assume is what OraTools is based on, and which they describe as a "C++ library that allows to develop cross-platform client/server applications in easy way. Native access to Oracle data gives high performance and all possible features. Furthermore OCL is simpler in using than OCI, more powerful than Pro*C and faster than ODBC."
(Well, not that *you* would want a *C++* library anyway! :-)
And in that same vein, [link|http://www.ensyncsolutions.com/|eNSYNC Solutions] offers a couple of free utilities (for Windows): Oracle Quick Check, "to check the health and status of your database", and Oracle Security Check, "to check for security holes using default usernames and passwords. "Download and learn more about your database in minutes!", is the promise for both. (They also say "You can learn a lot" -- about DB performance tuning and security -- "in just 5 minutes!" from their tuning page, which is also supposed to contain a set of sample tuning scripts.)
Finally, at [link|http://www.quests.com/|Quest Software], you'll find that old standby, the TOAD(*) (and apparently lots of other shit, nowadays -- just check the [link|http://www.quests.com/solutions/database_management_products_at_a_glance.asp|Products at a Glance] page).
There, HTH!
(*): Guess which major database company -- cough[link|http://www.oracle.com/|, ]cough -- has had such a hard time convincing *its own consultants* to eat the in-house "Enterprise Manager" dog-food that it recently had to concede defeat by acquiring several thousand TOAD licenses...? :-)