AR 15 types
http://vietnamresearch.com/manuals/m16.html (Army cartoon type manual)
http://www.archive.org/details/ArmyTechnicalManualforM16Rifle-Tm9-1005-249-23p (click on the "PDF" on the left side of the screen)
http://www.thefirearmblog.com/files/ar-15/TM9-1005-319-10.pdf (appears to be same as above, may be easier to download)
Ruger 10/22
http://www.ruger.com/Firearms/PDF/InstructionManuals/18.pdf (Ruger PDF for the 10/22)
Ruger Mini-14
http://www.ruger.com/Firearms/PDF/InstructionManuals/55.pdf (Ruger PDF for the Mini 14 Ranch Rifle)
http://www.ruger.com/Firearms/PDF/InstructionManuals/43.pdf (Ruger PDF for the 180 series rifles)
http://www.ruger.com/Firearms/PDF/InstructionManuals/23.pdf (Ruger PDF for the 181 and newer series rifles)
Ruger Mini-30
http://www.ruger.com/Firearms/PDF/InstructionManuals/25.pdf (Ruger PDF for the Mini 30)
M1 Garand
http://www.kmike.com/M1/m1.htm (FM 23-5 PDF)
http://www.fulton-armory.com/tea/tm9-1275.htm (TM 9-1275 PDF)
http://www.civilianmarksmanship.com/fieldstrip.html (CMP pictorials on field stripping, detail stripping and reassembly)
http://www.ar15armory.com/manuals/M1Garand.pdf (TM 9-1005-222-12 PDF)
M14/M1A
http://www.biggerhammer.net/manuals/fm23_8/FM23_8A.pdf (FM 23-8 PDF)
SKS
http://will.mylanders.com/shot/sks/
http://www.thefirearmblog.com/files/sks/china%20sports%20SKS%20manual.pdf
http://www.rt66.com/~korteng/SmallArms/sks/SKS-56_Manual.htm
AK47
http://guns.wolfcrews.com/ak47/pdf_files/US_Army_AK.pdf
More to follow