Allegro NFS Server — source code is open source; prebuilt binary is gratis for non-commercial usage.

Crossmeta NFS Services from Pavitrasoft — proprietary.

Cygwin NFS Server and Client — open source under GPLv2.

DiskAccess (client) and DiskShare (server) by Shaffer Solutions Corp. LLC (formerly from Intergraph Corp.) — proprietary.

Distinct NFS Server by Distinct Corp. — proprietary.

InterDrive Client 4.0 for Win95/NT by NetManage, Inc. (formerly FTP Software) — proprietary.

Microsoft Services for Unix (formerly Interix from Softway Systems, Inc.) — proprietary: gratis download, for MS-Passport users).

NFS for SmarTerm from Esker Software (formerly Persoft) — proprietary, apparently discontinued.

nfsAxe from LabF (gratis download, proprietary, US $40 to use long-term).

NFS Maestro by Hummingbird Connectivity Technologies, Inc. — proprietary.

Omni-NFS by XLink Technology, Inc. — proprietary.

PathWay Client NFS by Attachmate Corp. — proprietary, apparently discontinued.

PC-Xware by PCD — proprietary.

ProNFS by Labtam Inc. — proprietary.

Reflection NFS Client by WRQ. — proprietary.

Rumba Office 95/NT for TCP/IP by NetManage, Inc. (formerly Wall Data) — proprietary, apparently discontinued.

Solstice Network Client for Windows from Sun Microsystems, Inc. — proprietary, discontinued; firm recommends WRQ's Reflection NFS Client, instead).

SOSS-NFS (Son of Stan's Server NFS) — open source under GPLv1.

SuperNFS by Frontier Technologies Corp. — proprietary.

Term Professional by Century Software — proprietary, apparently discontinued.

War NFS Daemon by Jarle Aase (now unmaintained) — proprietary, gratis usage for non-commercial purposes.

Alternative: Use Samba. (Most people trying to do NFS on MS-Windows are solving the wrong problem.)