It is possible to method to make apache (eg: with the .htacess file) base the default filename for any directory url around the directory title itself? I possibly could do that one directory at any given time by modifying the httpd.conf for your directory, but it might be handy to have the ability to do that inside a more global/recursive kind of way.

Good examples to hopefully clarify:

http://example.com/dir1/ => would load http://example.com/dir1/dir1.php

http://example.com/some/long/path/ => would load http://example.com/some/long/path/path.php

http://example.com/jumboHotdogs/ => would load http://example.com/jumboHotdogs/jumboHotdogs.php

Possibly using DirectoryIndex? Or Mod Rewrite? Is even possible?

Mod_rewrite can certainly do this, try:

RewriteEngine On
RewriteCond %{REQUEST_URI} /([^/]+)/$
RewriteRule ^ %{REQUEST_URI}%1.php [L]