Naomi Bates is based in Texas and is known as one of the queens of the book trailer. She regularly makes recommendations on LM_NET which are always well-received.
Pamela Thompson is a prolific US reviewer, contributing regularly to LM_NET
The incarnation of an online project started years ago called the Young Australian Readers’ Awards and focuses on YA books read and reviewed by students. Its co-ordinator Stephen James knows more about YA than anyone I know.