General:
* Sky blue
* Azure
* Pale blue
* Powder blue
* Baby blue
* Cerulean
* Aqua
* Cyan
More specific:
* Robin's egg blue (a specific shade of light blue)
* Periwinkle (a bluish-purple)
* Lilac (a pale bluish-purple)
* Cornflower blue (a vibrant light blue)
The best word to use will depend on the specific shade you're trying to describe and the context.