You might consider Bookends Pro - it can handle thousands of
references and is much less expensive than most of the other
commercial products.
I think Sensible Software sells it - 800 394 4669
Al Fornace
Lab. of Molecular Pharmacology, NCI
Building 37, Room 5C09
National Institutes of Health
Bethesda, MD 20892
phone (voice): 301 402 0744
phone (FAX): 301 496 5839
email: fornace at ncifcrf.gov