My old GD works
Many are broken, just display blank page or error message. Listed below are still good readable fews;
https://sohmod.hopto.org/misc/gdsam/image11.php
https://sohmod.hopto.org/misc/gdsam/image1.php
https://sohmod.hopto.org/misc/gdtutor/colorallcalpha.php
https://sohmod.hopto.org/misc/gdtutor/ellip.php
https://sohmod.hopto.org/misc/gdtutor/polyf.php
https://sohmod.hopto.org/misc/gdtutor2/polyf_watermark.php
https://sohmod.hopto.org/misc/gdtutor/poly.php
https://sohmod.hopto.org/misc/gdtutor/str.php
https://sohmod.hopto.org/misc/gdtutor/watermark.php
https://sohmod.hopto.org/misc/gdtutor2/bar_shapes_ncolors_A.php
https://sohmod.hopto.org/misc/gdtutor2/bar_shapes_ncolors_B.php