<p>I am not a fan of using SQL*PLUS as an interface to Oracle.  I usually use <a href="http://sourceforge.net/projects/yasql/" rel="noreferrer">yasql</a>, but it hasn't been updated since 2005 and can do with some improvements.  A quick <a href="http://www.google.com/search?q=sql*plus+replacement" rel="noreferrer">Google search</a> shows yasql and <a href="http://www.sqlpal.com/" rel="noreferrer">SQLPal</a>.  I am using linux, so SQLPal is not an option.  </p>

<p>Are there any alternatives out there, or am I stuck with an interface that I do not like or one that is no longer maintained?  </p>

TOAD is pretty expensive, but you can download a 90-day trial from the Quest site to see if it's got the feature set you want (don't be fooled by the "freeware" title - it's only free for 90 days, and then it expires, which definitely makes it shareware):
http://www.toadworld.com/Freeware/ToadforOracleFreeware/tabid/558/Default.aspx
Another options is a tool I've seen on CodeProject:
http://www.codeproject.com/KB/database/OQuery.aspx
It's in .NET, so you'd have to see if it compiled on Mono, but it might be worth a shot. I haven't used either tool (Toad or this one), since I'm a SQL Server guy, but I've heard good things about Toad.