If you want an application that can handle both Oracle and MySQL, you might want to try "dbRadar". There is a demo you can download for free, and registration is $49.95 for the download only version, and $59 for the CD.
I haven't messed with Oracle for a while now, mainly been using Sybase when I need that kind of 'power', which they provide some tools for. I have heard about the [ulr=http://www.aquafold.com/]Aqua Data Studio[/url] that agusgriego mentioned...the general consensus was it does and ok job. Haven't tried it out myself though.