G.A.P. Adventures
G.A.P. Adventures often runs specials in which you can receive 20 percent off the total cost of the trip simply by booking at the last minute. These trips leave anywhere from a week after you book to two months after. The specials change fairly often, and if you check back every week, you can find many available deals. Bolivia, Kenya and Greece are examples of offered trips.
Intrepid Impulse
Intrepid is a travel company with its own system that handles last-minute vacation packages. The company books certain trips in advance and then offers the leftover spots at a discounted price. Two weeks before the trip departs, those deals appear on the site. Booking late saves you 20 percent off the cost of the package and gives you access to destinations such as New Zealand and Tibet.
Mountain Travel Sobek
Mountain Travel Sobek plans trips months in advance and accepts reservations for those trips from customers. The company guarantees a certain number of seats and if the trip isn't full, the company offers discount. The down side is that only two to four new customers can book those trips, but those who do, save at least $200 off the total price. Many of the trips involve adventure or extreme sports such as rock climbing.
Outdoor Trips
Outdoor Trips doesn't offer trips, but it is a great resource. This website lists last- minute travel deals and vacation packages, along with contact information or information on booking the trip. Many of the trips take place in the United States, but trips to Mexico, Pakistan and other countries are available. Activities include hunting, fishing, camping and white water rafting.