Fierce SSO is a Single Sign-On module for Drupal. It is designed so that if users log in to any one of your sites, it will automatically log them in to all the sites in the "network". It works by embedding special, invisible GIF images on the Welcome screen that users get after they log in. These images connect to the other sites in the network and silently log you in.
Fierce SSO is an alternative to danielc's singlesignon module (which does some magic by manipulating session tables in the background instead of using invisible images). I think my module uses a simpler approach and is more seamless to users. However, it occasionally fails if users have images turned off or if they navigate to another page after logging in without waiting for the page to finish loading.
Content Access allows you to manage permissions for content types by role and author. It allows you to specify custom view, edit and delete permissions for each content type. Optionally you can enable per content access settings, so you can customize the access for each content node.