Kevin Kelly has a rave review of a slide/negative scanning company called Scan Cafe. Here's how it works: send off your slides and negatives to Scan Cafe, they catalog and send them off to India to be scanned, you go online to choose the which negatives/slides you want final scans of, and in a few weeks, you get your originals and a DVD containing 3000 dpi scans of your photos. Kelly says:
Some people are very concerned about sending their precious originals to India -- or anywhere for that matter. They should not be. ScanCafe has a very elaborate tracking and shipping system that would work even if you were shipping jewels. Their scanning facilities in Bangalore (description and photos here) are more organized than you are. I have more trust in this system than I would handing them over to any neighborhood scanner.