I set up owncloud yesterday, and it seems to be very nice.
But when I wanted to open it outside my network over SSL, it got stuck in a redirect loop.
Now, I use pound as a reverse proxy to balance requests over several servers and to do SSL termination. This proved to be the problem, owncloud did not detect that the connection was SSL enabled despite the "X-Forwarded-Proto: https" header added by pound (which fixed similar problems in other webapps).
But luckily, just adding "SetEnv HTTPS on" in the Apache vhost fixed that!