Where to download legacy Mac OSes

System 1.x (disk image files)
http://www.nd.edu/~jvanderk/sysone/

System 3.0 and 3.0.1
ftp://ftp.ucalgary.ca/pub/micros/mac/system/System_7.1.x/

System 6.x.x and System 7.x.x
http://download.info.apple.com/Apple_Suppo...m/Older_System/

System 6.0.3, 6.0.5, and 6.0.8
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...m/System_6.0.x/

System 7.0 and 7.0.1
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...m/System_7.0.x/

System 7 Tune-Up 1.1.1
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...m/System_7.0.x/

System 7.1
ftp://ftp.ucalgary.ca/pub/micros/mac/system/System_7.1.x/
Update 3.0 (for 7.l, 7 Pro v7.l.l, 7.l.2)
ftp://ftp.ucsd.edu/pub/mac/apple/7.system.updates/

System 7.1.2 for Quadra
ftp://grijan.cjb.net:21000/macintosh/Soft...20for%20Quadra/

System 7.1.2 for PowerMac
ftp://grijan.cjb.net:21000/macintosh/Soft...for%20PowerMac/

System 7.5.1 Update 1.0
ftp://ftp.cs.tu-berlin.de/pub/mac/sys/upd...7.5_Update_1.0/

System 7.5.2 Update for PowerBook 5300, 2300, 190
ftp://ftp.cs.tu-berlin.de/pub/mac/mirrors...5300_SW_Update/

System 7.5.3 Update 2.0
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...7.5_Update_2.0/

System 7.5.3 Unity CD (binhex & MacBinary)
ftp://ftp.usask.ca/pub/mirrors/apple/Maci..._Version_7.5.3/

System 7.5.3 Unity CD (MacBinary)
http://download.info.apple.com/Apple_Suppo..._Version_7.5.3/

System 7.5.3 Rev 2.0 Update
ftp://ftp.cs.tu-berlin.de/pub/mac/sys/upd...7.5_Update_2.0/

System 7.5.5 Update
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...m_7.5.5_Update/

System 7.6.1 Update
ftp://ftp.usask.ca/pub/mirrors/apple/Maci...S_7.6.1_Update/
And thats all I could find. If you have any (legal) links to other versions, please post them up here