Box.net offers free 1GB accounts, and their servers run WebDAV. So here's what you need to do, in a nutshell:
- Set up your box.net subscription (easy and fast!).
- In iCal, publish your calendar (Calendar -> Publish) to https://www.box.net/dav, using your box.net account name (email) and password.
- Subscribe to the calendar in iCal (Calendar -> Subscribe) at http://www.box.net/dav/Your_Calendar.ics. NOTE: Do not use https here.
Shameless plug: I've written more detailed and illustrated instructions on my blog, but thought this might have wide enough appeal to share here. If you need more help, check out my detailed instructions.

