DC UltraFair.cgb
500 lines that have passed Dann Corbit's strict criteria (exit point evaluations plus database statistics)
http://kirill-kryukov.com/chess/discussion-board/download/file.php?id=31891

Xmas2640-12.cgb
A ChessGUI version of Mike Scheidl's opening book.
12000 lines with good variety.
Used to be a favourite of mine when testing with other GUIs.
http://kirill-kryukov.com/chess/discussion-board/download/file.php?id=31890