There is a free version of TOAD, an old, restricted version. It can’t do some of the stuff the commercial version can (I’m currently looking for migration tools) but it looks to be a much nicer way of talking to your Oracle DB than the Oracle tools.
You can get hold of it here.
I’m still having problems with Migration between Access and Oracle using ANY of the Oracle tools, especially Oracle SQL Developer, which throw all kinds of exceptions even when I try to do something as simple as import .csv data.
Get used to seeing “Feature available in commercial version” as I did on “Menu -> Database -> Import”. Why not hide these features instead of dangling the functionality in front of us! (obviously it’s to make you go out and buy the commercial version, but its still a bit annoying).