I have had an accident on my Debian-Archiv-Server and unfortunatly the files "Packages.gz", "Packages.bz2", "Sources.gz", "Sources.bz2" and "Release" from the directories
Afaict snapshot.debian.net has woody down to r4 and all point release of sarge and etch.For older point releases of woody you could grab the jigdo/template files for the CDs from http://cdimage.debian.org/cdimage/archive/jigdo/ , you will have to reconstruct a single big packages/release file set from the broken down ones on the CDs yourself though and unfortunately downloads of those .jigdo files seem to be hanging for me at the moment.
For potato I doubt you have much hope except for the last point release (which is availible on archive.debian.org).