Fujitsu makes some great ADF scanners, but most of them are professional-production level, which means "insanely expensive." (I think the ones we use at my job retail for ~$5,000.) Kodak has the same problem--the scanners that are top-of-the-line are industrial, not intended for personal use. (They work great for personal use. They're just pricey.)
I'm considering getting a Canon DR-2050C; Ebay
regularly has them for under $300. Was otherwise thinking of the
2010C.
If I had a few hundred dollars to put towards a book-conversion lab (and I want to), those would be my first choice--something that scans duplex, in color, up to 600 dpi. I don't want it attached to a printer or fax machine, and I don't need it to scan flatbed as well--I have a small flatbed scanner (Canon LIDE-30) for that.
400 dpi is good for OCR. Ability to *not* scan in color is important. Ability to scan to multipage Group IV tiff is important to me, but some people use different methods and won't care about that.
ABBYY FineReader is *the* software to use; whether you'd be happy with FR 6 (which comes with some scanners) or would want one of the later versions, depends on how comfortable you are learning complex software, and whether you care to convert anything more than novels. For just novels, almost any version will work. For textbooks with images, captions, graphs and so on, you may want more control & options than the cheaper software offers.
I'd love to tell you what keywords to look for for the right kind of scanner, but I haven't found any. Drum scanner, sheet fed scanner, ADF scanner... none of them work consistently.