I've seen a lot of references to www.blackmask.com (http://www.blackmask.com) being a good source of ebooks, but I've never been able to access the site. The connection always times out. Do they still exist?

This might answer your question

http://www.blackmask.org/

There have been some updates at TeleRead, for example:
http://www.teleread.org/blog/?p=5441
http://www.teleread.org/blog/?p=4827
or a list of many mentions here.... http://www.teleread.org/blog/index.php?s=Blackmask