I was lucky enough to come across a Three-spined Rainbow Skink (Carlia triacantha) resting on the warm paving tiles recently. They are often somewhat dull in colour, but some are striking with a bright blue head that is indicative of a breeding male. The darker tail in this case is due to regeneration, as it may have lost it in a near-miss with a predator. Upon being sprung, the male flicked his tail in the air and waved it around, while strutted along the pavement. The shaking of tails in skinks and geckos is thought to be a form of communication, when they are excited about food or when they are searching for a mate. In this case, it is likely to be the latter of the three due to the colouration of the male.
You can also watch the short video of the Rainbow Skink walking (sadly, I wasn’t able to capture the tail shaking):