Omnifocus for iPad
1. Tap settings gear in the upper righthand corner of the lefthand pane.
2. Tap 'Sync Setup'.
3. Tap 'Custom Sync with WebDAV'.
4. Tap the Address field, and enter "https://dav.dropdav.com/" followed by the path to the folder you want to store the OmniFocus database. Don't forget a trailing slash on the end!
5. When you're done, tap 'Sync' in the upper righthand corner.
6. Enter your DropDAV email address and password.
7. Tap 'OK'. You're all set!