Not for slides, but one of my scanners has a photo feeder.

I can put a stack of pics in the top and it'll automatically scan them all. It's been great.

Bryan - what brand/model of scanner are you using?

Nikon Super coolscan 5000
 

with the slide attatchment that holds 50 slides. It jams but it is one of the best slide feeder/scanner combos. Digital Ice is NICE, comes with it.

It is sweet and worth every penny, got my set-up on ebay at half price. Many folks buy the scanner and slide feeder then sell it after they are done, they are always available on ebay and some package them together. Probally a little over $1000 bucks. You can also scan negative film. The quality is tops. I personally don't ever want to see another slide ever again, after 10,000 I have had enough, it is very time consuming. You will also like the Nikon program because you can scale 1000,s of slides at once. very important when you have 3000 slides that has to go on one set of cds, you can figure if they have a HD plasma or SD box and scale your pics accordingly.