Select (or other)

From the project page: "Provides a new Forms API element which is a select/radios/checkboxes element that has an 'other' option. When 'other' is selected a textfield appears for the user to provide a custom value."

Real Name

"The RealName module allows the administrator to choose fields from the user profile that will be used to add a "real name" element (method) to a user object. Hook_user is used to automatically add this to any user object that is loaded. It will also optionally set all nodes and comments to show this name."

Video Filter

Lets you use tokens to embed video and have the ability to add a button to the WYSIWYG for easily adding a video (for those to0 lazy to type).

Insert

Insert is the easy, secure way to let editors add images and links to files using WYSIWYG editors.

Flag

Flag is the ultimate bookmark tool. A must learn module.