FireShot is a Firefox extension that creates and edits screenshots of web pages.

Unlike other extensions, this plugin provides a set of editing and annotation tools, which let users quickly modify captures and insert text and graphical annotations. Such functionality will be especially useful for web designers, testers and content reviewers.

Screenshots can be saved to disk (PNG, JPEG, BMP), copied to clipboard, e-mailed and sent to external editor for further processing.
Tired of silly utilites that grab only currently displayed area of the page?

FireShot extension integrates with Firefox and provides capturing both entire web page and only currently visible area