Such as Imaging Resources (and google some, too).

I have an older Nikon Coolscan III (SCSI inteface) which works well.

Some points to consider:
1. Look at [link|http://www.hamrick.com/|VueScan], which runs on Windows, OS 9/OS X, and Linux. I have it & like it.
2. Canon has a new model out that's competitively priced and worth considering.
3. I wanted something with automatic retouching software (similar to Nikon's DigitalICE which can remove dust spots by focusing on different layers); the less re-touching I have to do, the better.
4. If you're going to scan APS, get something which automatically advances the film, so you can let it scan a whole roll without intervention.
5. If you're going to scan 35mm negatives, go for something that can automatically advance the film, so you can scan a whole strip at a time without babysitting the unit.
6. If you're going to scan a lot of slides, consider getting a unit which can have an automatic slide loader.
7. Consider looking at someone like [link|http://www.publishingperfection.com|Publishing Perfection] which has refurbished units. I got my Nikon from them as a refurb at a great price (their normal prices typically aren't the best).

Tony