WordPress
WordPress Codex - The official online manual for WordPress.
WordPress 101 - This is a WordPress video tutorial series, a must have for learning how to run your WordPress website.

General Hosting
cPanel User Guide
cPanel Mail User Guide

MDDHosting
Client Area (provides access to cPanel and webmail)
MDDHosting Knowledgebase
MDDHosting Video Tutorials
Server Status

StableHost
Client Area
Support Center
Knowledgebase

Resources

1Password - 1Password is a password management program compatible with Mac (iPhone and iPad too) and Windows. Creating and managing secure passwords is critical.

Super Duper - Super Duper is a hard drive backup and system recovery program compatible with Mac.

Other World Computing - While geared towards the Apple platform, OWC offers a wide variety of hard drive products for media storage and backup.