This first photo was taken in Red Rock Canyon at the start of the "Tunnel Pitch" on Tunnel Vision (III, 5.7). If you're not familiar with this route, it is an absolutely stellar ascent. On the fourth pitch, one has the opportunity to actually climb through the mountain in a tunnel. In other words, the route requires a bit of vertical spelunking.
The top of the third pitch, at the start of the tunnel, it is difficult to see or hear the second. The route follows a corner and chimney system up the wall. In order to see my climber, I built an anchor and then, using the rope, extended the anchor to the edge where it was far less difficult to see and hear.
Some might argue that this system lacks redundancy. I'm not too worried about that as I can see the whole anchor to ensure that there is no rubbing and we never have redundancy in the rope while we're climbing with a single line...
This last picture shows a close-up of the figure-eight and the clove-hitch mentioned above.
One last thing to be aware of is that dynamic climbing ropes stretch 8-12%. Usually there isn't much rope in the anchor so there's not going to be that much stretch, but this should be taken into account before the system is loaded.
Flexibility and thinking outside the box are two major tenants of climbing efficiency. One way to be efficient and to be flexible and to be outside-the-box is to use your rope for anchoring instead of other materials. Your rope is always on you and as such, it definitely provides an option that really shouldn't feel like it's that far out-of-the-box...
--Jason D. Martin