Well, I've been tracking the IP addresses used by Nigerian scammers, and have been blocking them from our site, and this has been about 50% effective.
I'm tracking more, and also including the scam gangs operating from Ukraine and Romania.
Way down, I blogged the dilemma we're in, being fairly rabid civil libertarians and yet doing the right thing for the victims of crime. In practice, we've been lucky, for our size we don't get much abuse, and it's mostly harassers and scammers.
That's largely due to the culture of trust we have.
I guess this weekend I gotta do more, probably block more ISPs serving Lagos, even though I'll be at sxsw.com, on the road.