Morrus said:I think that, in general, a site has to have a unique niche for me to look at it more than once. There are hundreds of sites out there which already do the same things as each other (including EN World, I might add).
Something which covers a particular aspect of D&D better than all the others is the important thing, I think. The main example which comes to mind is Scott Greene's Creature Catalog - it deals exclusively with new and converted monsters, and it does that very, very well.