Dominions II Grimoire
http://www.sangster.org/dominions/grimorie.php was quite nice tool.
There have been fan-made (sometimes printable) pdf guides with color codes for showing various items for both DomII and Dom3. I can't give you any links, but hopefully someone can provide a link. It's nice for seeing what you can forge with spesific paths, but you can't easily compare different ways to achieve things. Item guide in which you can search for e.g. items that grant lightning resistance and/or immunity, or for items that grant reinvigoration - that would be very nice.