Google Street View has sent people on bicycles around 30 major archaeological sites in Mexico, including Chichen Itza, Palenque, Monte Alban, Teotihuacan, Tulum, Cobá, and more. You can go right up to (but not up) the pyramids. For me, seeing the tourists and the souvenir vendors is part of the fun. Daniel Hernandez at the LA Times has some more good links.
EcoAlberto Park in El Alberto, Mexico, offers a unique experience: participating in an illegal border crossing. VICE Magazine filmed the trip.
It's border-smuggling re-packaged as a tourist experience. According to the New York Times, this is "one of Mexico’s more bizarre tourist attractions: a make-believe trip illegally crossing the Rio Grande from Mexico into the United States." Perhaps your fully-paid border simulation will soon include being shot at...
Guidelines for Low-Impact Tourism Along the Coast of Quintana Roo "Conserving the natural landscape and enhancing the scenic beauty of tourism development contributes to the high quality of coastal habitat, one of the area’s principal attractions." Warning: PDF format!