I haven’t checked the links yet, but Yasin Soliman’s article for Graham Cluley’s site looks really useful. How to report a cybercrime – Who you gonna call? includes a table with contact points in the US appropriate to several categories: I’m guessing that followers of this blog will find the links for ‘Internet fraud and SPAM’ particularly relevant. There are also links to agencies in other parts of the world.
The trouble with compiling such lists of links (which I’ve done many times over the years, in a variety of contexts) is that the links change over time, not only because web pages get changed around, but because agencies (like security companies) are renamed or replaced, or disappear altogether. Right now, though, this looks like an excellent resource.