The Koch brothers, their family members, and their employees direct a web of financing that supports conservative special interest groups and think-tanks, with a strong focus on fighting environmental regulation, opposing clean energy legislation, and easing limits on industrial pollution. This money is typically funneled through one of three "charitable" foundations the Kochs have set up: the Claude R. Lambe Charitable Foundation; the Charles G. Koch Charitable Foundation; and the David H. Koch Charitable Foundation.
Other resources:
Koch Industries profile on SourceWatch, a wiki project of the Center for Media and Democracy
Ongoing blog content on Koch Industries from ThinkProgress, a project of the Center for American Progress Action Fund
Koch Brothers Exposed video series from Brave New Foundation
Center for American Progress Action Fund report: The Koch Brothers: What You Need to Know about the Financiers of the Radical Right [PDF]
Center for Public Integrity report on Koch federal lobbying activity: Koch