Al Qaeda (whatever the name now is) provides training, combat experience in various theaters (e.g., Kashmir), funding (although the organization only puts up some of the funds for any given operation, expecting other groups to provide "matching funds"), expertise, and a network of supporters and agents in place. Operatives needing to travel can move between safe houses run by bin Laden cells.
While theories that the organization is short on cash cannot be confirmed, they are certainly frugal. The hijackers in the 11 September attack literally mailed or wired their remaining cash to Mustafa Ahmed, the Al Qaeda paymaster in the UAE, a couple of days before the attack. Those who took pilot training often negotiated deals to pay half of the $5000 fee up front, then dropped out of class after learning the cockpit instruments and how to maneuver the aircraft in the air. Operatives live modestly and, when traveling, stayed in budget hotels. One of those involved in the Millennium plots was given only a few thousand dollars and instructions in how to rob banks to get more.
Al Qaeda began with bin Laden's personal fortune (estimated to have peaked at $300 million). Bin Laden was a highly successful fund raiser during the Afghan War (against Russia), encouraging donations from rich Saudis and other Arabs, and from his own relatives. A number of Islamic charities siphon off funds to Al Qaeda, and some bin Laden operatives run various operations (such as credit card scams) to raise more money. Rich Arab businessmen make donations that amount to protection money.--Stephen V Cole
Inside Al Qaeda- The organization created by Osama bin Laden, known as Al Qaeda ("the base"), merged earlier this year with the Egyptian organization Islamic Jihad. This has improved the organization and discipline of Al Qaeda, which has been renamed. US intelligence officials are debating if the new name is Al Qaeda Jihad (the base of the holy struggle) or Al Qaeda Jadid (the new base).