I had time for fiddling around with Oracle Application Express (APEX) and could justify it as part of Oracle 11g product evaluation. Some notes follow.

When you use the database creation assistant with 11g, it generates a script called apex.sql, which in turn executes $ORACLE_HOME/apex/catapx.sql. That seemed to work OK, except there is a fair amount of configuration afterward. And Oracle Text really needs to be installed in order for apex help files to display correctly.

So here’s my list of stuff to do if you want to install Application Express.
1. Install Oracle Text first. $ORACLE_HOME/ctx/admin/catctx.sql. Check that all objects in dba_objects are valid and that components in DBA_REGISTRY are valid.
2. Run $ORACLE_HOME/apex/apexins.sql. Review the log file and make sure the entry in DBA_REGISTRY is valid. For older versions, you may need to run $ORACLE_HOME/spex/catapex.sql.
3. Review and then execute the steps in the Oracle Application Express documentation. You want the Application Express Installation Guide. It explains quite a bit, including how you can run either the Oracle http web server (Apache) or the web server that’s inside the database called embedded PL/SQL gateway. Pick which web server you want and follow the appropriate instructions. Be sure to remember the password you supply when running $ORACLE_HOME/apex/apxconf.sql. You’ll need it to do admin work with APEX.
4. Something not mentioned anywhere that I saw was the listener.ora change you need to ensure that embedded pl/sql gateway works. Adding this in the DESCRIPTION_LIST worked for me:
(DESCRIPTION= (ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=8080))(Presentation=HTTP)(Session=RAW))
Thanks Tim Hall of http://www.oracle-base.com for pointing this out on your web site!
5. At point I was able to log in using http://%5Bhostname%5D:8080/apex/apex_admin, using user ADMIN and the password supplied in step 3 above!