I have always been interested in high-speed photography. The ability to shoot in the dimmest environments handheld is one of the coolest things to me.
35mm film has a couple of very high-speed emulsions available, namely Kodak T-Max 3200 and Ilford Delta 3200. I have shot both and have found my best results to be with T-Max 3200 (or TMZ) developed with XTOL undiluted at the times listed in Kodak's technical publication.
TMZ is technically only a 1000 ISO film or so that is push-processed to get to higher speeds. The film can be pushed to extreme levels, up to 25,600 according to the literature. I have most frequently shot this film at 6400, which is usually the speed I need for shooting wide-open (f/2 usually) handheld at 1/60 of a second shutter speed or so (or 1/125 at f/1.4).
I shot a roll of TMZ last night at a Halloween event featuring 4 bands. The lighting at this bar is abysmal, with just a few bare-bulb lights in the ceiling providing all available light. In situations like this I usually shoot digital, but it is a lot of fun to use my Nikon SP as well, though there is a much better margin of error on digital. I currently use a Nikon D700 camera which is still really clean looking at 6400 and is even okay at 12,800.
First here is several images from the Nikon SP over the course of the evening. Almost all were taken with the 85mm f/2 lens wide-open at 1/60. Because push-processing increases the contrast of the negatives, the shadows are mostly pitch-black and the highlights get blown out easily, so an adjustment curve is often necessary to get a good range of tones (usually an inverse S-curve, with low values bumped up and high-values down.):
The limitations in image quality is pretty clear, but at the same time the effect is dramatic and for this type of subject I think enhances the photo.
In digital, at 6400 ISO, I was able to get much cleaner files. Here are a couple for comparison. The Nikon D700 is probably the best performing camera at high ISO save for the Nikon D3S, making it especially good at this kind of photography. As with any digital camera though, colors get pretty ugly at high ISO (as well as with the terrible lighting at this bar) so I usually shoot these in b&w:
While the image quality is obviously better on digital, which one is subjectively "better" is entirely up to you.