Don't underestimate the success bringing influence of good and professional looking design.
Well it a matter of taste...
I personally really like the default theme bundled with 2.6 (Called renaissance).
But if someone comes with Web Design skills willing to help, i'm all ears open.
Well, the one I have seen is the JBoss Portal Demo
It's artistically interesting, but I think it is not targeting the professional business audiences.
Is there a theme directory? (like portlet swap...)
How do I look at the renaissance theme? by installing?
Ok, i see.
Portal.demo.jboss.com is outdated (That's JBoss Portal 2.2)
The new one is unfortunately not available online.
You should install JBoss Portal 2.4 or JBoss Portal 2.6 (Get the Portal+AS version, then it is just a matter of unzipping and running run.bat)