My scanner came with a flat plastic widget that holds about 5 slides. The scanner cover has a cord that, when connected, illuminates the slides from above. The scanner software then recognizes that the source is slides and separates them into individual files.
It's an Epson, but it's pretty old - in technology terms, anyway. I think the max resolution is 1200 dpi, so the scanned slides probably wouldn't make for very good enlargements. They're good enough for prints, though.
Depending on what you want them for, you might look around at current scanners.