An essential resource for all Anchor fans is George Hardy's superb Anchor website: http://www.ankerstein.org. Be sure to check it often. George updates it monthly.
A great many additional building designs are available for downloading here.
Special ornamentations (clock faces, windows, figures, etc.) are available for downloading in pdf format here and also here.
A catalog of Anchor stones is available for downloading here. You'll find line drawings and dimensions of each stone as well as an inventory of stones for each modern set.
Robert Stegmann maintains a fantastic puzzle site, including information about older Anchor puzzles. Be sure to see http://home.comcast.net/~stegmann/tangram.htm for starters.