I used a 1 mm nozzle with Slic3r (set to 0.6 mm default extrusion width, and 15 mm/s print speed) to make a adjustment knob for a coffee grinder that had broken off (cause it was originally thin, weak, and made cheap). This worked very nicely. The pictures don’t do it justice as the actual part is much less glossy and more clean looking.
Also, a “Stanford Bunny” was printed from thingiverse, scaled up to a 100 mm long base. This is a large part – up to 120 mm tall (so the ears cut off in my print!). Previously a bunny was made (hollow, layer thickness = .25 mm, time = 4.5 hours) with the 0.5 mm nozzle. The same exact bunny was printed again, with the same settings except 0.05% infill was added, and I used the 1 mm nozzle, and took about 3 hours. The part feels an order of magnitude strong and is very noticeably more filled in along steep contours. It is also about 2.5 times the weight in plastic. Take a look at pics and you will see. New (1 mm nozzle) bunny right, old (0.5 mm) bunny left. You’ll notice much better quality overall, better bonding, and no loss of feature resolution in any way.
Update 11/12/12 – The surface has since been improved much more by expanding the nozzle-flat surface to include about 3 mm diameters.