There is a growing body of data pertaining to non-precinct-place voting available online. Much of it is still scattered around state, county, and other local offices, but there are several useful datasets and resources.
Election Day Survey
The US Election Assistance Commission (EAC) has run a national Election Day Survey every two years since 2004. The data on election administration and voting collected from local election officials are publicly available on the EAC's website. While early survey data are largely incomplete (for many survey items) and prompted serious academic criticism, later iterations of the survey have improved dramatically. Moreover, the Election Day Surveys are on their way toward creating an incomparable time-series dataset of election administration and voting metrics in the US.
Non-Precinct Place Voting in the States 
Jonathan Nagler (New York University), Jan Leighley (University of Arizona), Nathan Cemenska and Daniel P. Tokaji (University of Ohio) compiled a dataset of state laws governing non-precinct place voting across the country. The dataset runs from 1972 through 2008 and includes the relevant statutes at each presidential election within that period.
Ballot Integrity and Voting by Mail: The Oregon Experience
As part of the Carter-Baker Commission on Federal Election Reform, Dr. Gronke submitted a memorandum outlining Oregon's vote-by-mail experience. This map was intended to help the Commission identify best practices for vote-by-mail systems, highlight potential pitfalls, and guide the Commission’s deliberations as they evaluated the rapid expansion of by-mail voting.
See also the full commission report.
Election Administration in the United States
Joseph Harris's landmark 1934 book on election administration, available in full on the NIST website.