MerenthaInfo Forum - Discuss anything you want about Merentha.
Merentha Collective - Includes a calculator that helps you out with stat/skill costs as well as many other helpful tools for playing Merentha.
Merentha Underground - Has lots of good information about Merentha. Unfortunately not kept up too much anymore.
The Children of Merentha - Newer site with some unique information, maps, equipment lists, etc.