For me, the big lesson of the episode of the errors in the paper by Carmen Reinhart and Kenneth Rogoff is, Show your work. From the time they released their first working papers drawing on the data they would use in their book This Time Is Different, they have been slow to release the data. When I reviewed their book for the Cato Journal about a year and a half after it was released I complained that they still had not yet posted much of the data online.
Before the Internet there was no convenient way to make data readily accessible to anyone who might be interested in it. The best one could expect was that the authors or a journal that published their work would store it in a file and send copies on request. For at least the last decade, though, there has been no excuse for failing to make data available online if it is potentially important and if it does not violate copyright restrictions or confidentiality agreements. Reinhart and Rogoff could have posted their data and calculations immediately and their error might have been detected much sooner, allowing them to correct their results at an early stage with less embarrassment.
For future work on free banking using historical statistics and making calculations, authors should post the spreadsheets or computer code. They should also describe the original sources precisely, so that other researchers can find them, and where the sources are not already available online and are out of copyright, it would be very helpful to post digital photographs showing the data. In fact, a central repository of text and data on free banking would be enormously helpful because it would enable researchers to avoid duplicating effort collecting material. I have been informally helping to organize a similar repository concerning currency boards (easier than for free banking because the data are more centralized, but still requiring an enormous amount of work, mainly done by students in this case). It will go online later this year, at which point I will write a post about it.
I have tried to practice what I preach with my book The Bretton Woods Transcripts (e-book 2012, hardcover forthcoming in a few weeks). Although the book does not contain any statistics or calculations, it did require significant editing of the original transcripts of the Bretton Woods conference. My co-editor Andrew Rosenberg took photos of the original typescripts of the conference at the National Archive and we posted them on the publisher's Web site. Readers who want to compare our edited book to the original typescripts can readily do so.