Geckos Unlimited - Yann Fulliquet provides a nice informational set of photos illustrating the differences between male and female grass lizards.
Lampropelma sp. ‘Borneo’ Sexual Dimorphism
Arachnoboards - Some very clear macro shots of pre-maturity dimorphism in the Lampropelma sp. ‘Borneo’ tarantula. Many tarantulas only become visually dimorphic at sexual maturity, so this is very useful for breeders working with this yet unclassified species.@ Arachnoboards