The Adoption Social is the place to go to start meeting other adopters online. They have all sorts of things going on, with all sorts of bloggers contributing.
Adoption UK is somewhere else to go to find out about adoption, and link up with other adopters. Especially relevant if you want to find out why adopted children need a different type of parenting is the Wall
BAAF is an organisation with a lot of information about adoption and fostering. It also produces many, many useful books.