Algaebase (Biotechniques again) is a database of images and bibliographical references to algae, 120000 species of them. You can search by genus or species from boxes on the home page, or search the literature, images, common names, distribution and other things from the Search option on the home page.
The database is compiled by Mike Guiry at the National University of Ireland and copyright and conditions of use are outlined here
. Some papers about Algaebase are listed on the About