Attached to this post are PDF's of the service manuals for all the Power Mac G4's, iMac G4's, PowerBook G4's and iBook G4's. Enjoy :)
g4cube.pdf - G4 Cube enclosure replacement instructions
airport.cube.pdf - G4 Cube Airport card replacement instructions
battery.cube.pdf - G4 Cube Battery replacement instructions
harddrive.cube.pdf - G4 Cube Hard Drive replacement instructions
memory.cube.pdf - G4 Cube Memory replacement instructions
PM_G4_1999-01.pdf - Power Mac G4 (AGP Graphics/Gigabit Ethernet/Digital Audio/QuickSilver), Power Mac G4 (PCI Graphics), Macintosh Server G4 with Mac OS X Server, Macintosh Server G4
Power Mac G4 2002.pdf - Power Mac G4 / Macintosh Server G4, Power Mac G4 (AGP Graphics/Gigabit Ethernet/Digital Audio/ QuickSilver/QuickSilver 2002/QuickSIlver 2002ED), Power Mac G4 (PCI Graphics), Macintosh Server G4
pmg4_mir_fw800.pdf - Power Mac G4 (Mirrored Drive Doors), Power Mac G4 (FW 800)
emac.pdf - The first eMac
eMac_2002_03.pdf - eMac (ATI Graphics)

Continued:
eMac_2004_05.pdf - eMac ATI Graphics / USB 2.0 / 2005
imac_usb2.pdf - iMac (USB 2.0)
imac.17-inch.pdf - iMac (17-inch Flat Panel)
imac.flatpanel.pdf - iMac (Flat Panel)
iBook G4 early2004.pdf - iBook G4 / Early 2004
ibook_G4_12.pdf - iBook G4 (12-inch Late 2004)
ibook_G4_14.pdf - iBook G4 (14-inch Late 2004)
Apologies, could not upload them all due to file size restrictions here.
(PowerBook G4 Titanium) pbg4_dvi.pdf - PowerBook G4 (DVI)
(PowerBook G4 Titanium) pbg4_ge.pdf - PowerBook G4 (Gigabit Ethernet)
(PowerBook G4 Titanium) pbg4.pdf - PowerBook G4

Continued:
(PowerBook G4 12 Inch Aluminum) pbg4_12in.pdf (2003 edition) - PowerBook G4 (12-inch), PowerBook G4 (12-inch DVI)
(PowerBook G4 12 Inch Aluminum) pb_g4_12.pdf (2005 edition) - PowerBook G4 (12-inch) PowerBook G4 (12-inch DVI)
(PowerBook G4 12 Inch Aluminum) pbg4_12in_1_5ghz.pdf - PowerBook G4 (12-inch 1.5 GHz)
(PowerBook G4 12 Inch Aluminum) pbg4_12in_1ghz.pdf - PowerBook G4 (12-inch 1.33 GHz)

(PowerBook G4 15 Inch Aluminum) pb_g4_15.pdf - PowerBook G4 (15-inch FW800)
(PowerBook G4 15 Inch Aluminum) pbg4_15_fw800_15ghz.pdf - PowerBook G4 (15-inch FW 800), PowerBook G4 (15-inch 1.5/1.33GHz)
Apologies, could not upload them all due to file size restrictions.

(PowerBook G4 17 Inch Aluminum) pbg4_17in.pdf - PowerBook G4 (17-inch)
Apologies, could not upload them all due to file size restrictions.

Also unable to upload the Mac mini G4 service manual due to the file size restrictions. That's all I have, enjoy!

Thank you! Amazing information-heaven!

Terrific stuff. Thanks!