Re: commendable. But...
"What could possibly go wrong?"
Well, anonymity is pointless. Unless every unverified report or accusation is fully investigated, then being anonymous doesn't help one bit. And even then, the circumstantial evidence often points to one or a very small number of people.
A bigger concern is the treatment of whistleblowers who are traced. Here in the UK PIDA isn't worth the bog roll it is printed on. Didn't help Dr David Kelly, did it? Likewise my friend and former colleague who reported a serious fraud at a listed company. As a result three directors and two others were sent to the big house, but he's not worked since, not been compensated for his actions, and a subsequent well founded allegation of malpractice at a large and dodgy Scottish bank has been repeatedly ignored, stonewalled and "long-grassed" by UK government and regulators.
My advice to potential whistle blowers: Don't report it, you will lose out. Don't get involved, it is probably illegal. If it is the state, you're stuffed - go along with it after creating a suitable paper trail of questioning the behaviour, and then accept the official assurances that it is all above board. If it is the private sector and there's no violent criminals involved, do try and maximise your chances by asking for a golden goodbye under a comprehensive NDA if they so wish. And do stick to the NDA - why make your own life uncomfortable for no reward?
If somebody offers you a web site for whistleblowing, just laugh and keep walking.