Tourism:
Mexico Tourist Board
MexOnline.com
US State Department on Mexico

Active Adventure

Golf Resorts

Regions:

Baja California:
All About Cabo
Baja Travel Guide
Visit Cabo
Visit Los Cabos

Copper Canyon:
Turismo al Mar
Viajes Flamingo
Native Trails

The Pacific Coast:

Mazatlan:
Mazatlan Tourism Office
Mazatlan Interactivo
Pronatours
Mazatlan Surf Center

Puerto Vallarta:
Puerto Vallarta Tourism Board
Vallarta Adventures
Open Air Expeditions
Chico's Dive Shop
Rancho El Charro - horseback riding
Coming About - women-only sailing school
Canopy Tours de Los Veranos
Four Seasons Resort Punta Mita
Hacienda San Angel
Quinta Mar’a Cortez
Velas Vallarta Grand Suite Resort
Verana

Ixtapa/Zihuatanejo:
Zihuatanejo Tourism Office
Ixtapa-Zihuatanejo.org
La Casa Que Canta
NH Krystal Ixtapa
Villa del Sol
Villas Miramar

Acapulco:
Skydive Acapulco
Camino Real Acapulco Diamante
Hotel Elcano
Villa Vera Hotel & Racquet Club

Mexico City:
Mexico City Secretary of Tourism
MexicoFile.com
Habita
Hotel Camino Real
Hotel Four Seasons Mexico City
The Marguis Reforma
La Casona Hotel-Relais
W Mexico City

Yucatan Peninsula:
Yucatan Travel Guide
Mexico's Yucatan
Trek America - active trips in Yucatan and Chiapas
Cozumel.net
Cozumel Travel Planner
Travel Notes
Cozumel Hotel Assn
Viva Cozumel
Riviera Maya Tourism Board
Playa Magazine Online
Club Akumal Caribe
Captain Ricks Sportfishing Center
Akumal Dive Shop
Hotel Na Balam - Isla Mujeres
Mysterious Places: Chichen Itza
Hacienda Chichen