Yes, there is exist one very nice open-source tool developed as extension for Oracle SQL Developer - called GeoRaptor. You need to download Oracle SQL Developer from OTN and GeoRaptor from http://mygeoraptor.googlepages.com/. Installation instructions for GeoRaptor are provided also on the same site.
That's great, best free SQL -Editor I've ever seen and the plugin: GeoRaptor....(Geometry-View-Function !!!)...
=> A perfect double to work with spatial data.
P.S. The Plugin can also be downloaded by sourceforge, I got some problems with the direct SQL -Editor-Update-Function:
Direct Link: http://prdownloads.sourceforge.net/georaptor/org.GeoRaptor-20060202-dev.jar?download