Fnding info about german U-Boots of that era is nearly a nightmare, so any more webs dedicated to that are always wellcomed
I suppose you know already Heinrich Lang's (aka Deamon) project to build a WW1 sub simulator, which has a forum also here (Imperial U-Flotilla). You can browse there as there are tons of links and useful stuff to enrich your web
P.S. a section dealing with technics would be really nice (Tools, machinery, etc.)