Today, the large-scale compromise of Internet hosts serves as a platform for supporting a range of criminal activity in the so-called Internet underground economy. In this talk I will quickly survey work that our group has performed over the past decade on the problems posed by these threats, and how our research directions have evolved over time. In the remainder of the talk, I will describe recent work that our group has performed, including the ecosystem of CAPTCHA- solving service providers and an end-to-end analysis of the spam value chain. Using extensive measurements over months of diverse spam data, broad crawling of naming and hosting infrastructures, and product purchases from a wide variety of spam-advertised sites, I'll characterize the relative prospects for anti-spam interventions at multiple levels. -- This work is part of a larger effort within the Collaborative Center for Internet Epidemiology and Defenses (CCIED), a joint NSF Cybertrust Center with UCSD and ICSI, and an ONR MURI collaboration.