Salvete,
Topica wouldn't let me in until now, so I guess I'm a little late with the links we had so far, but anyway, here goes :
Roman architecture, sculpture, painting
http://harpy.uccs.edu/roman/html/roman.html
Roman literature
http://www.thelatinlibrary.com/
Roman Glass making
http://www.umich.edu/~kelseydb/Exhibits ... Glass.html
The Villa Rustica in Hechingen-Stein
http://www.villa-rustica.de/intro/indexe.html
Etruscan Art
http://www.ou.edu/class/ahi4163/files/main.html
Ancient Manuscripts
http://www.nb.no/baser/schoyen/
Everyone is invited to send in the addresses of more websites of course and if someone should have trouble finding a decent website about any subject related to Roman art, then feel free to ask here and we'll (hopefully) find something.
Valete optime!
Lupus