And from this weekend's Washington Post, an article about #32 on the list above,
 hiking the Inca Trail.  
(Ups and Downs on The Arduous Trail To Machu Picchu, By Eric M. Weiss, Sunday, November 23, 2003).
Here's some key info that follows the article:
GETTING THERE: Most major airlines, such as American and Continental, fly to Lima from Washington, with at least one connection; fares start at just under $700 round trip. From Lima, it's a one-hour flight to Cuzco on LanPeru, among other carriers, for $185 round trip.
WHEN TO GO: Weather in the Andes is unpredictable year-round, but the trail is closed in February, and January and March can be muddy slogs. June, July and August find the biggest crowds.
WHERE TO STAY: Staying near, but not in, Cuzco's main plaza allows you to be near the attractions, restaurants and tour operators but far enough away for some peace and quiet. There are many hotels in all price ranges. We enjoyed the Royal Inka 1 (299 Plaza Regocijo, telephone 011-51-84-222284 or 011-51-84-231067, 
www.royalinkahotel.com), a historic mansion built 300 years ago, with rates of $78 per night double.
TOUR OPERATORS: We used Andean Life (011-51-84-221-491, 
www.andeanlife.com), which offers a four-day tour for $260 per person, including all meals and transportation to and from Cuzco. Other reputable outfitters include SAS (011-51-84-237292, 
www.sastravelperu.com) and Explorandes (011-51-1-4450532, 
www.explorandes.com). Book as early as possible.
WHAT TO BRING: High-tech hiking wear for layering, good broken-in hiking boots, rain/wind gear, sleeping bag, headlamp-type flashlight, sun hat and glasses, and camera. Prepare to experience all four seasons in a single day.
INFORMATION: For general information on Peru: Embassy of Peru, 202-833-9860, 
www.peruvianembassy.us(Spanish only), or the Commission for the Promotion of Peru, 
www.peru.org.pe. One of the best Web sites on trekking the Inca Trail is 
www.andeantravelweb.com, which has good links for preparation and other information.