Clifford Connor gives a pretty good starting point in his book A People's History of Science, which happens to be sitting next to me right now, so I'll basically summarize what he says and dig up all his references that I can access for you.

While sources clearly show that Amerindians were indeed used extensively in the “discovering” and mapping of the new world by colonizers, this fact is largely ignored in literature on the history of cartography. Columbus relied heavily on native Americans geographic knowledge and drawn maps when available, going as far as taking an old Indian as a slave onto his ship “since the savage could draw a sort of chart of the coast.” In 1534, Jacques Cartier abducted two native Americans named Taignoagny and Dom Agaya, transported them to France, taught them French, and brought them back to guide him up the St. Lawrence River.

Another example of this can be found in what has been called “one of the most influential pieces of cartography in the history of the United States,” Captain John Smith’s highly regarded Chesapeake Bay map. Used for over 70 years and known for its detail and relative accuracy, Smith’s map acknowledges the “significant input of Amerindians who guided, instructed, and informed him and his associates as they painstakingly explored the wilderness during the first months and years of Virginia’s founding.” This is not atypical of how geographic knowledge was obtained throughout the colonization of the Americas.

Typically given credit for his discovery of the source of the Mississippi River in 1832, Henry Rowe Schoolcraft was only able to do so “because an Ojibwa chief [Ozawindib] guided him and his small expedition to the site.” During his exploration of the St. Lawrence Valley region, Samuel Champlain wrote:

“I had much conversation with them regarding the source of the great river and regarding their country, about which they told me many things, both of the rivers, falls, lakes, and lands, and of the tribes living there, and whatever is found in those parts. ...In short they spoke to me of these things in great detail, showing me by drawings all the places they had visited. … Some things were cleared up about which I had been in doubt until they enlightened me about them.”

Possibly the most posthumously recognized Amerindian to date, Sacajawea, is on the US dollar coin precisely because of her contributions to the cartography of the United States by guiding Lewis and Clark on their historic expedition to the west coast. Herman Friis, who studied the published journals of the expedition cites “at least thirty direct references to Indian-made maps and some ninety-one descriptive statements of a geological nature by Indians,” as well as stating that Lewis and Clark “faithfully copied most of the maps the Indians traced out for them on a sand-swept surface, on a smooth bark, and on a leathern chart.”

Known to be the best 17th Century work on New France for “its detailed descriptions of the environment as well as north american native society,” Baron de Lahontan writes in his 1703 book, New Voyages to North America, that Amerindians,

“Draw the most exact Maps imaginable of the Countries theyre acquainted with, for there's nothing wanting in them but the Latitude and Longitude of Places: They set down the True North according to the Pole Star; the Ports, Harbours, Rivers, Creeks and Coasts of the Lakes; the Roads, Mountains, Wood, Marshes, Meadows, etc.”

Yet another example, John Lawson writes in 1709 describing his travels through uncharted parts of North Carolina:

“They will draw Maps very exactly of all the Rivers, Towns Mountains and Roads, or what you shall enquire of them… These Maps they will draw in the Ashes of the Fire, and sometimes upon a Mat or Piece of Bark. I have put a Pen and Ink into a savage’s Hand, and he has drawn me the Rivers, Bays, and other Parts of a Country, afterwards I have found to agree with a great deal of Nicety.”

It shouldnt be forgotten as Weatherford notes in Native Roots, that “Kidnapping Indians and forcing them to become interpreters, guides or slaves grew into a well established cultural pattern among explorers. Such practices became a standard part of the business”