Hardware

Apple Spec Database
Specifications on many models of Macintosh hardware.
http://www.info.apple.com/support/applespec.html

Disassembly of an Apple Pro Keyboard
Ripping apart an Apple Pro Keyboard and giving it a thorough cleaning is presented in painstaking detail.
http://www.technology.niagarac.on.ca/people/bgracey/prokeyboardrepair.html

Engadget: Turn your Mac mini into a media center
Covers the various aspects to think about when planning a Mac mini media center system, plus shows how to control a Mac mini headlessly from any computer in the house.
http://engadget.com/entry/1234000057028826/

EveryMac.com
A complete guide to every Macintosh and Mac clone with technical, configuration, and pricing details. Technical specs and Q&As.
http://www.everymac.com/

Gear Live - Why Apple Makes a One Buttoned Mouse
Apple system software has supported a multiple-button mouse for many years, but here's some reasoning behind them selling one-button mice.
http://www.gearlive.com/index.php/news/article/why-apple-makes-a-one-buttoned-mouse-01280820/

Hardware Developer Documentation
Apple's developer's documentation for hardware including computers, cards, and peripherals.
http://developer.apple.com/documentation/HardwareDrivers/

HP - Macintosh Compatible Products
Direct link to a listing of everything sold by Hewlett-Packard that works with a Mac.
http://www.hp.com/sbso/printing/mac/

MacGurus Motherboards Database
Mac motherboard layouts for Macs prior to the Power Mac G5.
http://www.macgurus.com/products/motherboards/mgwhichram.php

MacInfo.de
PowerPC Mac hardware information, benchmarks, and test results. In English and German.
http://www.macinfo.de/

MacWorld's Mac Hardware Guide
MacWorld magazine's reviews and ratings of Macintosh hardware.
http://www.macworld.com/product/hardware/index.html