Check
here. They are the one company left that does this sort of processing on a small scale (per roll basis rather than commercial basis) - Snap3D I believe. From what I hear, their service is good and they are reliable to deal with. DO NOT send your film to anyone that you cannot contact first, and even then I would at least scan the negatives before sending them out. I sent film and payment to a place called Click3D once because they sent me mailers right away when I requested them. As it turned out, they took the money and my film despite the fact that they were bankrupt already - they just kept sending out mailers on demand because they were right foul gits as they say. Snap3D on the other hand, are supposed to be good and have a long(ish) reputation for being very good to work wtih, so I wouldn't worry about them as much, but I would still make scans. For the latest info on them, check the Yahoo! group photo-3d - they are the best source for information of this type that I've seen.
There is really nothing quite like a large lenticular print. I'm a stereoscopic nut anyway, but these things are really cool. No glasses need, just your eyeballs and the print. I wouldn't get all my photographs done in this fashion due to cost, but if it were cheaper I'd not get tired of this format easily. I keep meaning to send off for 5-6 8x10 prints - everything that I have right now is quite small, but still really fun. I'd love to get some of my better Realist slides printed in this fashion...
- Randy