Blueprints
Blueprints is designed to bring a visual representation of Structure templates to the Publish Page, and easily show the user what fields are available in each template.
Expression Engine Add-ons
Custom System Messages
Custom System Messages provides an alternative to one of the most annoying things with EE, which is the fact that all error messages, regardless of type or severity are filtered through the same template, which is only editable within the Control Panel, and it doesn’t even parse other template tags.
WYMeditor for ExpressionEngine
This is a custom field type to give you an WYMeditor, or What You See Is What You Mean, in ExpressionEngine 2.0
Current URL (Extension)
Current URL is an extension that adds some helper variables and makes them available in your templates.
Redeemer (Module)
Redeemer is an ExpressionEngine module for managing coupon codes.
Anonymous Member (Plugin)
Create a completely anonymous member to take advantage of some modules or features that require a user to login.