There's been a major update over at old-computers.com, with increased information on 4 Sinclair machines (Spectrum, Spectrum+, ZX81, and QL). Updates to the standard Spectrum page are listed as "Motherboard explained, Inside Microdrive, Inside microdrive cartridge, Discovery FD, Inside Discovery, Printer Floyd 40, Wafadrive, Inside Wafadrive, Wafadrive cartridge." Should provide a good opportunity to get... inside the Spectrum.
Ooh and look, the computer of the day (for the next 15 minutes-or-so) is the ZX Spectrum +3. It really is a good day.