I recently found out about this one: anonymously.io
A few questions that comes to mind are these:
Why would you want to use something like this in the first place?
Would you ever consider to use something like this as a freelancer?
To me, it seems like anyone using these, would have a good reason to do it if they did illegal things, but that's about it. I can't come up with a good reason for using this if you're doing everything legally. Can you?