Here at CH we hold a healthy skepticism toward conventional travel packages, but the offerings from Wilderness Travel are a welcome exception. The Berkeley-based organization focuses almost exclusively on off-the-beaten-path destinations and the kind of risky endeavors that justify their professional supervision. Their goal is to take people outside the normal tourist agenda to partake in pro-active, outdoorsy type activities.
The current crop of trips goes to all seven continents and includes a trek up Mount Chomolhari in western Bhutan and a snorkeling/kayaking trip on Myanmar's Mergui Archipelago (pictured below left). They also offer more classic adventurer fare, like hiking Everest and cruising the Galápagos islands—but Wilderness specializes in the obscure.
The 2008 catalog features detailed information on over 100 trips, with plenty of vivid images on heavyweight paper. You can order one for free on their site.