Package tours are simply a way to buy the airfare, accommodations, and other elements of your trip (such as car rentals, airport transfers, and sometimes even activities) at the same time and often at discounted prices.
One good source of package deals is the airlines themselves. Most major airlines offer air/land packages, including American Airlines Vacations (tel. 800/321-2121; www.aavacations.com), Delta Vacations (tel. 800/654-6559; www.deltavacations.com), Continental Airlines Vacations (tel. 800/301-3800; www.covacations.com), and United Vacations (tel. 888/854-3899; www.unitedvacations.com). Several big online travel agencies -- Expedia, Travelocity, Orbitz, Site59, and Lastminute.com -- also do a brisk business in packages.
Travel packages are also listed in the travel section of your local Sunday newspaper. Or check ads in the national travel magazines such as Arthur Frommer's Budget Travel Magazine, Travel + Leisure, National Geographic Traveler, and Condé Nast Traveler.