. Here is an impressive list of PhD theses|dissertations repositories from around the world: http://bit.ly/IPiY3e
. One important thing about this list is that unlike many the old fashioned database of the past, most of these repositories are Open Access (OA).
Very useful link; thanks. It is, however, useful to note that in some cases, all of the dissertations/theses listed are very recent (i.e., recent enough to have been submitted in pdf). The library at my UK university has just e-mailed asking my permission to scan my
(oops, forgot UK usage) thesis from the 1970s with a form e-mail reporting that they are "just beginning to consider scanning older dissertations and theses."