I have added two additional sites to the list at the side.
One is Sancta Missa which is a series of resources for those using or interested in the Extraordinary Form of Mass. It is produced by the Canons of St John Cantius in Chicago, where they are restoring a church and using the traditional liturgy. I met one of their number at the CIEL conference at Merton a few years ago, and impressed by what they were doing.
The other is that of the Society of St Hugh of Cluny which is also concerned with promoting the use of the usus antiquior. Based in Connecticut many of its posts are specific to the US, but it has articles of interest to those of us further afield.