Borenstein, Nathaniel S., and Ned Freed, "MIME (Multipurpose Internet Mail Extensions): Mechanisms for Specifying and Describing the Format of Internet Message Bodies", RFC 1341, Proposed Internet Standard, June, 1992.
Borenstein, Nathaniel S., "A User Agent Configuration Mechanism For Multimedia Mail Format Information", RFC 1343, June, 1992.
Borenstein, Nathaniel S., "Implications of MIME for Internet Mail Gateways", RFC 1344, June, 1992.
Borenstein, Nathaniel S., and Mark Linimon, "The Extension of MIME content-types to a New Medium", RFC 1437, April 1, 1993.
Borenstein, Nathaniel S., and Ned Freed, "MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies", RFC 1521, Draft Internet Standard, September, 1993.
Borenstein, Nathaniel S., "The text/enriched MIME Content-type", RFC 1523, September, 1993.
Borenstein, Nathaniel S., "A User Agent Configuration Mechanism For Multimedia Mail Format Information", RFC 1524, September, 1993.
Borenstein, Nathaniel S., "The text/enriched MIME Content-type", RFC 1563, January, 1994.
Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, Internet Standard, December, 1996.
Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, Internet Standard, December, 1996.
Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC 2049, December, 1996.
Borenstein, N. and M. Kucheraway,
"An Architecture for Reputation Reporting", RFC 7070, November, 2013
Borenstein, N. and M. Kucheraway,
"A Media Type for Reputation Interchange", RFC 7071, November, 2013
Borenstein, N. and M. Kucheraway,
"A Reputation Query Protocol", RFC 7072, November, 2013
Borenstein, N. and M. Kucheraway,
"A Reputation Response Set for Email Identifiers", RFC 7073, November, 2013
Tomkinson, N. and N. Borenstein, "Multiple Language Content Type", RFC 8255, October, 2017
I've also published over a dozen internet drafts, early documents on the standards track. Most of them are early versions of what eventually became the above RFC's, but a few others are still interesting:
The application/green-commerce MIME Content-type was a speification of the MIME type for First Virtual's payment model.
The Simple MIME eXchange Protocol (SMXP) This was a protocol for exchanging transactions like First Virtual's, only designed to be broader.
The Green Commerce Model is an explanation of the fundamental model and trust architecture of First Virtual payments.
KidCode: Naming Conventions for Protecting Children on the World Wide Web and Elsewhere on the Internet Without Censorship was a proposal for marking pornography on the Internet to protect children. It would have been much better than what actually happened.
A User Agent Configuration Mechanism For Multimedia Mail Format Information This described the "mailcap" format that became an informal standard for specifying how to handle MIME types without ever becoming a formal standard.
The application/pgp MIME Content-type This specified how PGP should be encoded in MIME.
One Planet, One Net: Principles for the Internet Era This was an unsuccessful attempt to involved the IETF community in CPSR's "One Planet, One Net" campaign (see above).