Interesting article in Time. Here's just a schnibit:
A bewildering variety of groups — some seeking money, some pushing a terrorist agenda — have kidnapped dozens of foreigners since the end of the war last year. The hostages then become commodities in a deadly human trade that links street gangs to local mafias to insurgents like Abu Mousab al-Zarqawi, the al-Qaeda — linked jihadi thought to be behind many of the recent terrorist attacks in Iraq. Victims are sold up the chain, and each handler scores thousands of dollars, money used to finance gun running, drug smuggling and the insurgency...
The West generally is aware of only kidnappings that are politically motivated, like the abduction and subsequent beheading of American businessman Nick Berg. But the practice is far more common, and the kidnappers — the men who initially seize the innocents — are often petty criminals. "Those who take the hostages are not sophisticated," says Andrew White, director of the Iraqi Center for Dialogue, Reconciliation and Peace. "They're thugs, gangsters."
The best hope for springing a hostage comes at the initial stage. Groups like White's contact mosques, tribal leaders, militias and even former intelligence agents in search of news about the victim. Because the low-level gangs are after cash, a quick payout might free the hostage before he is "sold up" to groups with less easily deciphered, deadlier agendas. Such deals can be lucrative: prices paid range from $10,000 to $100,000, according to White, with U.S. soldiers fetching the highest rate.