Forums:
Insectes.org
Lepiforum (Forum)

Photographs of Moths and Butterflies:
Moths and Butterflies of Europe and North Africa
Butterflies and Moths of the Netherlands
Butterflies and Moths of Norway
Butterflies and Moths of Northern Ireland
Les Carnets du Lépidoptériste Français
Euroleps
Schmetterlinge und ihre Ökologie
Familie Roths Naturfotos
Lepiforum (Classification)
Odezia atrata

Photographs of Butterflies:
Butterflies of New Zealand
Butterflies of Mexico
Matt's European Butterflies
Butterflies of Bulgaria

Photographs of Moths:
UK moths
Zygènes des Alpes Maritimes
Schmetterlinge aus Oberbayern

Photographs of Larvas:
Lepiforum (Larvas)
Ukleps.org
Gallerie-Chenilles
Larvae of North-European Lepidoptera
Raupen

Butterfly Farms:
Butterfly and Orchid Garden (NZ)
Australian Butterfly Sanctuary (AU)
La Serre aux Papillons (FR)
Butterfly Creek (NZ)
Wildlife Sydney (AU)

Others:
Fauna Europaea
Database of the World's Lepidopteran Hostplants