>Barcode label printers.

I use the Monarch products; Pitney Bowes sells their big, fast, form-oriented barcode printer as the J690. They're available in serial and USB configurations, and are smart printers; you define a label form, including details on fonts and positioning and pre-load the printer with the details, and then generate labels by sending a stream that designates the form to use and the fields to fill. It's not cheap, but it is blazingly fast, and handles many of the details of barcode formation and positioning much better and with less CPU overhead than stuff relying on the Windows GDI to form graphics output. It handles a wide range of stock, and creates consistently legible, properly positioned output very quickly.