For example, you can set your home address in Downcast or Instapaper so that when you leave or arrive, those apps will fetch new content without you having to open the app. Downcast will even download the podcasts in the background.

Now, this requires you to move outside the fence, so it's not time based. But I had a decent system where I had my work and home address in Downcast and I set it to fetch whenever I leave or arrive. My regular commute meant that I was always triggering the geo fence.