Tread carefully, politicians – concerned citizens are watching your every move on the web. Their tools? Custom data mashups that use public databases to draw correlations between every vote cast and every dollar spent in Washington.

Take this report about the widely debated and bitterly fought California SB217, which would have banned clear-cutting in ancient forests.

Generated by the nonpartisan MapLight.org website, the report clearly shows that the logging industry, which opposed the bill, gave nearly twice as much money to politicians as environmental groups did. The bill was defeated.

Sites like Maplight.org, Opensecrets.org and Follow the Money, along with wiki-based political reporting resources like Congresspedia, are increasingly giving ordinary citizens the ability to easily document the flow of special-interest money and how it influences the legislature.

These new tools are providing an unprecedented level of transparency, exposing patterns of influence that otherwise would have remained invisible to ordinary citizens.

"Prior to the web, you'd have to visit a secretary of state's office and sort through paper records," says MapLight.org executive director Dan Newman. "The level of access that's now available to anyone at the click of a button is just tremendous."

Sheila Krumholz, executive director of the Center for Responsive Politics, or CRP, the organization behind Opensecrets.org, says, "It's always been the case that there are too many stories in this data set for one class of people to mine. From our perspective, the more eyes, the better."

Anyone – from bloggers and students to lobbyists and activists – can use these sites to quickly drill down into the correlation between a politician's vote and the money he or she received from special interests. The graphs and reports are easily shared or posted on a blog. The sites give access to data by legislator, bill number, bill subject or special interest.

Next month, MapLight.org will extend its database, which currently only tracks the California legislature, to include data from the 110th U.S. Congress. The site will also roll out a custom reporting tool that will let users add their own data. If the data is accepted by an administrator, it will be included in the central database.

Say someone learns at a cocktail party that the airline industry plans to oppose an upcoming bill. With the relaunch, that information can be added to MapLight.org's list of industries opposing the legislation. The information won't be added to the public database until it is verified by the site's admins, but it will show up in the user's custom report, which they are free to share.

MapLight.org's open-data initiative epitomizes a technique known as "database journalism," a new reporting paradigm that allows citizens to act as consumers, custodians and contributors to vast wells of information stored in web databases.

A survey conducted last month by Opensecrets.org found that 45 percent of its users identified themselves as "interested citizens" rather than journalists, activists, educators or political consultants. Further, 59 percent of its users said they use the site for personal – not professional – reasons.

In the past, Krumholz says, Opensecrets.org counted the press as its "No. 1 client," a relationship becoming less and less necessary as citizens begin to research political topics themselves.

"In the era when (the mainstream media) was all that existed, an organization like ours would probably have the resources to do custom analysis for the few reporters who requested it," says Krumholz. "Now with hundreds of thousands of blogs and niche publications added to the mix, there's no organization that can afford to do the custom research and analysis for these outlets."

MapLight.org builds its database from a variety of public sources. Legislators are required to file campaign contribution information, which is processed by The National Institute on Money in State Politics and the CRP.

MapLight.org's automated scripts scrape legislators' voting records from government websites. Public testimonies, official congressional records and news databases provide information on which special-interest groups support and oppose each bill. The congressional data for the mid-May launch is being supplied by the CRP.

MapLight.org and the CRP will be rolling out enhancements to their services throughout the year. Both organizations will also release application programming interfaces, or APIs, by the end of 2007, allowing web developers to create custom reporting tools based on the community's data.

Coming soon to a blog near you: Ajax widgets that track the effects of campaign contributions on congressional votes.

Just in time for the 2008 presidential primaries.