Algal Biodiversity
While primarily designed for students, this site from the University of Guam gives good
descriptions and illustrations of both freshwater and marine (benthic) algae from Micronesia

Australian Marine Algal Name Index
AMANI is a database based at Murdoch University of the taxonomy, nomenclature and distribution of Australian marine macroalgae.

CSIRO Microalgae Research Centre
CMARC is an Australian centre for excellence in microalgae research. It also develops and maintains a comprehensive culture collection and supply service of living microalgae to meet the needs of aquaculture and biotechnology industries in Australia and overseas.

Cyanobacterial Research
Site for the Department of Botany at Stockholm University. Research focuses on establishment and communication in cyanobacterial—plant symbiosis and ecophysiology, genetic diversity and cell differentiation in marine cyanobacteria.

Freshwater Algae
Census of Freshwater Algae in Australia is a joint project of the Australian Biological Resources Study (ABRS), the Royal Botanic Gardens, Melbourne, and the Royal Botanic Gardens, Sydney. Its aim is to provide simple access to information on the currently accepted names for Australian freshwater algae, their synonyms and their broad-scale distribution.

Spirulina
Good general information site mainly focusing on human health benefits of this microalgae. Also includes information on growing, safety standards and a health library.