Good quality Eurypterid web sites are few and far between, a typical web search will turn up over 300 sites but only a handful are really worth a look.  Here are a few of the best:
 

http://www.kheper.auz.com/gaia/biosphere/arthropods/eurypterids/Eurypterida.htm

http://www.extinctions.com/catalogs/hall/silurian2.shtml

http://members.tripod.com/~gknight/