I had previously skimmed the surface of "Ancestry Library" looking for information about my dad's family, but had never thought to search my own name. I have a fairly common name - Barbara Harvey; there are over 600 people in the U.S. alone with that name! But adding my middle name and birth date helped narrow the results. Still, in the first record, my previous address was incorrect. There was also someone else named Barbara Harvey, born the same year as I was, who had also lived in Cedar Falls, Iowa! I did notice other inaccuracies, and would caution anyone doing serious genealogical research to also use other sources of information, if possible.
A search of "South Dakota" restricted to photos and maps returned over 3 million results, including the Corn Palace, of course! (Haven't seen it in person yet).
HeritageQuest was more difficult to search (or at least more difficult to find any results). I searched some of the same people that I did in Ancestry, but no results. I think this database would be more useful for someone who has already done some genealogical research and is looking for more specific information.
In Sanborn Maps, I looked for the house I live in in Vermillion. I know it's old, but I don't know any specific history. I was able to locate my house on the 1923 Vermillion map (515 E. Clark):
I suspect it's older than that, but the earlier maps don't show this level of detail. Fun!
All three of these resources are excellent for South Dakotans wanting to know more about their history.