Sqldeveloper 2.* had a very good tool to view database schema. here is the screen-shot of how it can be launched:

Was this tool removed from SqlDeveloper 3.* and is there something similar there?
P.S. I tried googling and reading manuals for some time, of course.
The latest versions of SQL Developer still have the data modeler.
http://www.oracle.com/technetwork/developer-tools/datamodeler/overview/index.html
here’s a link that shows you, I use it almost daily in the latest version of sql developer (or at least 3.1.07 that I am using –>whoa they’ve updated to 3.2 I’ll go get that later)
you can still goto Tools->Data Modeler but you can also OPEN and SAVE the datamodeler via the File->Data Modeler context menus (it seems to have been ‘combined’ with SQL DEVELOPER to the point where you save it independently).
If you go to VIEW->Data Modeler->Browser you can then create models etc and save them via the aforementioned menu item in SAVE.