Now that you've managed to get Oracle installed, you'll want to try and use it. Although it's possible to do everything from your server PC, it's generally best to user the client-server facilities and use another machine to access your database.
Naturally Oracle have a large collection of, largely, pretty good client software, however there's not much for Linux at this time. The main useful piece of software, Oracle Enterprise Manager, usually comes with Oracle.
But most of the best software comes from other places...
Tool for Oracle Application Development (T.O.A.D.). This used to be free but is now owned by Quest Software. You can download a free version (if you're prepared to do it every couple of months) or you can pay for it. When I'm using Oracle on a daily basis, this is the program I choose if I have to use a Windows desktop. It's not as polished as some, but it does just about everything you need.
TOra. This is the closest you'll find to a TOAD for Linux. In fact, in some ways it's better than TOAD! The Linux version is free, but you can also buy a Windows version.
SQLNavigator. Also by Quest Software. I've not really used it but it's been highly recommended by all who have.
OraSoft. These guys produce applications for Oracle that actually run on Linux. I've not used them in anger, but they look good.
Orac. Another that I've not used much, but has been described as a nice, configurable DBA-tool by a number of people.