For hooking up an older scanner to a USB port? I think Adaptec makes one, but it is crazy expensive. http://www.newegg.com/app/ViewProductDesc.asp?description=12-193-001&depa=0 For a desktop, it would be cheaper to pick up a SCSI card on Ebay, but for a notebook it is most likely the only way to fly.
It's also only a 50 pin port - most likely a hard drive, unless it is REALLY old, is a 68pin Wide or 80 pin SCA, so you'd be looking at another adapter as well.