Developer by Chris Pederick. "The Web Developer extension for
Mozilla Firefox and Mozilla adds a menu and a toolbar to the
browser with various web developer tools." It will display alt attributes.
WAVE - helps people
perform design tasks that require human judgment (e.g. "Does
this ALT text provide a functional equivalent for this
image?"). The Wave displays the ALT and title attributes for
images as well as links to any long descriptions it encounters.