Suse hardware database
Redhat hardware database
Mandrake hardware database
hwb.sunsite.dk, Hardware Book, general hardware book, circuits, connectors ...
linux-usb.org, Linux USB hardware
Linux USB device DB
linuxprinting.org, Linux printer database
linux-laptop.net, Linux on Laptops, long list with different Laptop types
tuxmobil.org, Linux on Laptops and other mobile devices
xtops.de, Linux Laptops pre-installed [Deutsch]
linuxdevices.com, The Embedded Linux Portal
www.guiadohardware.net, Hardware and Linux site [Portuguese]

Connectors and pinout
Tommy's pinout collection
technick.net, General computer hardware info
Internet Hardware Book

Other hardware pages
linuxtoys.org, self made hardware for your linux computer