Two of my favorite answers (I wrote) both involving the role of religion in some American secular affairs, music and foreign relations.

How and why did Christian evangelicals and fundamentalists become such strong supporters of Israel and the Jewish people?

What were the views of Church on Blues Music?

I think we can just nominate /u/Reedstilt, and helpfully he has assembled a list of his greatest hits here.

Wait, are you only looking for things from 1492 onwards?

/u/Reedstilt consistently has awesome contributions for Native North American history in this sub. I know so little about it that region pre-17th century; I always learn something from his comments.

These are my favorites:

Was there a revolutionary ideological shift that brought down the Mississippian cultures?

What was happening in N. America during the time of Jesus?

These are all my answers I've submitted on American history. I don't know if any are of high enough quality to be considered, but I thought I'd share just in case.

American History

Political History

• Why was Washington D.C. created out of land owned by Virginia and Maryland?

• What was the deal with the Fenian Raids into Canada?

• Did Henry Clay's political platform while running for President change, or was it consistent?

Racial History

• Was there ever a serious effort to get Native American Nations to join the United States, and be recognised as states?

• During the Jim Crow/Civil Rights era, were there any boycotts launched against entire states?

• Why were sit-ins during the Civil Rights movement potentially dangerous affairs?

• [How did the N-word come to be a derogatory slur] (http://www.reddit.com/r/AskHistorians/comments/2v2d9u/how_did_the_term_ngger_become_derogatory_towards/)

• In the US, did slaves have any legal protections from their owners?

• To what extent was the emergence of strong black leaders reason for the increased demand for Civil Rights?

• What was Martin Luther King Jr. really like?

• Is it true that the original African slaves brought to Virginia were treated as indentured servants, and that they were eventually granted freedom?

• How accurate is the proclamation that Irish slavery was as prolific in America as African slavery?

• Did white indentured servants mix with black slaves?

• Is there truth in the statement, "The Civil Rights Movement made MLK, rather than MLK making the Civil Rights Movement"?

• Were there religious arguments against miscegenation? What were they?

Social History

• Were the Vietnam era protests effective?

• Why do we measure cultural shifts in decades?

• When did literacy become expected in America?

• How did marijuana come to be so stigmatised in the United States?

• What makes old Universities/Colleges more prestigious?

• Popular Music and the Vietnam War

I don't know if my answer to What was the role of improved travel and communication in the run up to the American Civil War? deserves to be in exalted company, but it is a favorite of mine. Someone liked it enough to feature it on the twitter feed.

As I've already crossed the self-promotion rubicon, I'm also fond of these answers:

When California was admitted to the union in 1850 were there debates about the month travel time to DC and the lack of a transcontinental telegraph? with follow up.

Does the American Civil War teach us about proximate vs. underlying causes? with follow up. I think this one also made the twitter.

My series of answers in this post are what I would consider my personal best.