The Capital Eye blog at OpenSecrets.org sets out links to information showing which sectors have paid how much money to which political campaigns.

The blog explains that it is difficult to fully understand this week's hearings on climate change in the US Congress without this data, including:

• "Overviews of federal campaign contributions by the energy sector over time. This breaks down into contributions from electric utilities, the mining industry and oil and gas companies. Automakers and the agriculture sector, among others, will also likely want to offer input as energy-related legislation moves forward. And, of course, we can't forget the environmentalists and alternative energy producers, who now appear to have a more prominent seat at the table.
• These industries also try to peddle influence by lobbying the federal government. Take a look at how much the energy sector, electric utilities, the mining industry and oil and gas companies spent on lobbying in 2008. For automakers, go here; for the agriculture sector, go here; and for environmental groups, go here.
• How much have individual members of Congress received from these industries? OpenSecrets.org can show you: energy sector, electric utilities, mining industry, oil and gas companies, automakers, agriculture, environmentalists and alternative energy producers. Play around with the dropdowns and slider menu to change the timeframe or see totals to specific members of the House and Senate. 
• Check out which industries gave the most to members of the various 110th energy-related committees (111th coming soon) by going here and selecting any of the following: House Energy and Commerce Committee; House Select Energy Independence and Global Warming Committee; House Science Committee; Senate Commerce, Science and Transportation Committee; Senate Energy and Natural Resources Committee; and Senate Environment and Public Works Committee.
• House Energy and Commerce Committee Chair Henry Waxman (D-Calif.) and Subcommittee on Energy and Environment Chair Ed Markey (D-Mass.) penned the cap-and-trade global warming bill before their committee this week. Take a look at their individual profiles to see where these two are getting their money, here for Waxman and here for Markey.
• For a look at how the various industries tried to influence energy-related legislation in the past, take a peek at Capital Eye's 2008 Power Struggle series and 2007 Power Play series."