UK
British Geological Survey Geoscenic - UK national archive of geological photos - free to download.

Earth Science Activities and Demonstrations - Mike Tuke's activities and demonstrations provide a thousand and one ideas for teaching Geology:
visual aids, demonstrations, short activities, paper exercises and experiments.

ESTA - Earth Science Teachers' Association: UK national association supporting geoscience education.

Geograph Britain and Ireland - the aim is to photograph every 1 km grid square in the UK - photos are free.

GeoHub Liverpool - Geoscience resources for teachers and students.

GSL The Geological Society of London - Education / Careers - resources

JESEI - The Joint Earth Science Education Initiative: resources to help biology, chemistry and physics teachers to teach Earth science.

GeoBus - educational outreach project supporting Earth Science learning in schools in the UK.

Schoolclimatescience.info - website that aims to provide teachers and students with the information they need to understand climate change.

UGUK - The Geological Society, University Geoscience UK

International
EGU - European Geosciences Union, dedicated to the pursuit of excellence in the geosciences and the planetary and space sciences for the benefit of humanity.

Geo Podcast - podcasts made on a wide range of Earth science topics. Most episodes are less than 15 minutes long and some have associated classroom activities.

ICASE - International Council of Associations for Science Education: international organisation of all science education associations.

IGEO - International Geoscience Education Organisation: organisation supporting geoscience education development and running four-yearly international GeoSciEd conferences.

IUGS - International Union of Geological Sciences: international organisation supporting geoscience.

IUGS-COGE - Commission on Geoscience Education: IUGS commission leading international geoscience education development.

Micro My Earth - Portal for geological resources, software, webinars and more to teach, learn and share geology in the classroom, at work and at home.

USA
AGIWEB - American Geological Institute: US organisation of geoscientists supporting geoscience education.

NAGT - National Association of Geoscience Teachers: the US association supporting Earth science teachers.

NESTA - National Earth Science Teachers' Association: the US association supporting Earth science teachers.

AGI - The American Geological Institute Earth Science World Image Bank.

Australian
ESWA - Earth Science Western Australia

Spanish
AEPECT - Asociación Española para la enseñanza de las Ciencias de la Tierra: La organización de profesores de Ciencias de la Tierra de España, Portugal e Hispano-América.

Italian
ANISN - Associazione Nazionale degli Insegnanti di Scienze Naturali.