I plan to eventually post some pictures of my single-speed 29er. Meanwhile, some random reflections on riding a single speed, which I have not done since I was several decades younger than I am now.
First, having only one gear doesn't slow me down as much as I thought it would. Today I rode 17 miles at an average of 13.3 mph. Not Tour de France record speed, but faster than I would have expected. I think I actually come up hills faster, since there's no choice but to stand up and push ahead. On a slight up-hill stretch, I spun out to 23.4 mph. Again, not a record, but not bad for the rough equivalent of 3rd gear on a road bike.
Second, it is in fact fun to not have to worry about being in the right gear. Yes, you can ride a multi-speed and leave it in one gear, but the thought of shifting would always be in the back of the mind. What's the point of multiple ratios if you don't use them?
Riding single-speed seems to have the potential to make one a stronger rider. Hills I stood up on the first few rides no longer call for leaving the saddle.
It seems to make climbing easier if the hands are spread wide, near the very ends of the handlebars.
Maintenance promises to be simpler--no derailleurs to adjust, no gear cluster to scrub.