I use Facebook for both personal and professional use, but I primarily use it for personal use. Here are a few pages that look interesting and worth some additional researching.
Kindergarten Smorgasboard - great photos and videos of a creative kindergarten classroom in action
Kindergarten Connection - some great free resources as well as additional resources available for purchase
The Literacy Nest - shares the importance of phonemic awareness and phonics in learning to read
I also follow our school's Facebook page as well as a private page for teachers and staff.