The on-again off-again archive of traditional Roman liturgical documents appears to be on-again. It is called the Archivum Liturgicum Sacrosanctae Romanae Ecclesiae, and is located here.
Take a look. It has tremendous potential. It has been updated regularly throughout the month of June. Hopefully, that will continue.
...I can now guarantee that the Archivum Liturgicum WILL REMAIN ON-LINE. We had a problem in the past, because in US someone registered our ancient domain (.org), but now we have our own domain and we will never desappear (God willing). I'm confident in your cooperation in promoting and supporting the Archivum. Yours in Christ,
Pietro Siffi, President