I am not a fan of using SQL*PLUS as an interface to Oracle. I usually use yasql, but it hasn\'t been updated since 2005 and can do with some improvements. A quick Google searc
It depends what you are looking for. If it is a GUI query tool, then Oracle have their free SQL Developer product (though it has a hefty footprint). There's a few free cross-database ones too. I like SQUirrel SQL client myself. There's also DBVisualiser and a few others. JEdit is an editor that has a DBConsole plugin for running database queries and DML/DDL. They are all java based so run most places.
If you like a command line, check out sqlpython (the developer has identified a couple of others too)