Harbrace College Handbook, the Chicago Manual of Style, and the foot-thick old Webster's dictionary for grammar and such.

I've found WordWeb to be a good little computer dictionary. You can download it for free. Amazing little tool.

As for as writing websites, absolutewrite covers just about every type of writing you can think of.

For submissions, duotrope and Preditors & Editors. The "Agents & Attorneys" link at P&E has a breakdown of reports received on unscrupulous organizations and people.