In terms of connections to UNIX services, like Telnet, NFS, and FTP; look at products like NCSA Telnet and others.
NCSA Telnet is a Macintosh telecommunications program written by the National Center for Supercomputing Applications at the University of Illinois, Champaign-Urbana. It provides a VT100 connection to UNIX systems that have Telnet services. NCSA Telnet also provides FTP (File Transfer Protocol) uploading and downloading and Tektronix 4010 terminal emulation. The most recent version of NCSA Telnet (version 2.2) supports direct connections to an Ethernet via an EtherTalk card (or the EtherPort cards from Kinetics) and connections over LocalTalk/PhoneNET through an AppleTalk-to-TCP/IP gateway, like the FastPath from Kinetics.
CAP (Columbia AppleTalk Package) is a public domain product from Columbia University that turns UNIX systems into AppleShare servers that can be accessed through the Chooser. It also provides various print services for those UNIX systems.
MacKermit is a public domain, serial-based telecommunications program providing VT100 emulation and uploading and downloading via the Kermit file transfer protocols. Most UNIX systems also have Kermit support, and this program provides good asynchronous access and file transfer capabilities to these systems.
Ungerman-Bass Corporation has announced Telnet and FTP programs for the Macintosh, based upon our announced, but not yet released, MacTCP driver.
uShare is a product from Information Presentation Technologies. uShare is comparable to PacerShare or AlisaShare, but for UNIX -- it is software that runs as a process under UNIX and permits the Sun systems that run it to act as AppleShare file servers. A Kinetics FastPath would still be needed to bridge LocalTalk and Ethernet.
Currently, there are no products that translate data files other than raw text files between Suns and Macintosh computers. Many of the terminal and file transfer programs listed above do this properly.