The Subchaser Archives covers the subchasers of WWI. If you are interested in the subchasers of WWII, here are some resources:
Theodore R. Treadwell's web site on SC type chasers in WWII:
Splinter Fleet, The Wooden Subchasers of World War II
William J. Veigele's works on the PC type subchasers in WWII:
PC Patrol Craft of WWII
Seabag of Memories