I keep a Git repository with the contents that I update from time to time - this makes it easier to do diffs against past versions: https://github.com/chalst/pollockhostsfork
If you want a smaller HOSTS file (useful with Windows) that only targets advertisement and tracking servers, I've found HP Hosts' ad_servers.asp list to be good.
http://someonewhocares.org/hosts/
I keep a Git repository with the contents that I update from time to time - this makes it easier to do diffs against past versions: https://github.com/chalst/pollockhostsfork