I often think of them as parasites as well, but the  analogy always makes me a little squeamish, as there is only one way to treat a parasite- exterminate it. However, I do think we need to Purge the PIRGs from any and all leadership of field operations. With the ways that these organizations have behaved over the past 20 years, they have absolutely no place within the progressive/liberal movement. It is the duty of the netroots/grassroots to stand up with our, to use Greg's analogy, proletariat brothers and sisters, and make sure that all of the organizations who are employed by "liberal" organizations adhere to the same standards we demand of others (transparancy, ability to take constructive criticism, treating workers with the respect they deserve).