O Happy Day! The wireless card in my Dell D620, which Dell calls a "1390", a mini-PCI-Express card with a Broadcom BCM4311 chip on it, works now. This card ships with lots of other laptops, Dell and otherwise. A patch, bcm43xx-2619.patch, (also for BCM4312) in the 2.6.20 changelog applies nicely to 2.6.19. (It appears you also need on-card firmware to be loaded from /lib/firmware, e.g. bcm43xx-firmware.tgz, to make it work.) Now maybe I can finally retire my orinoco cards. Now, too, maybe people will stop hustling ndiswrapper as some kind of holy grail. It was actually kind of hard to get this patch; the one in 2.6.20 mixed in other stuff, and the git web interface on kernel.org was borked. Copious thanks to Stefano Brivio and everybody else involved.
fejj: The way Bell Labs solved a similar problem (spell checking) on V7 UNIX was to hash each item several different ways, and set a bit for each result in a common bitmap. If hashes for the next URL find all those bits set, you've almost certainly seen it before. Extra credit for quantifying "almost certainly" according to bitmap size, number of hashes, and number of URLs.