Here's an "ftp" link :
<a href="ftp://gatekeeper.dec.com">FTP Link to Gatekeeper</a>
<p>
Here's a "gopher" link :
<a href="gopher://gopher.loc.gov">Gopher Link to Library of Congress</a>
<p>
Here's a telnet link :
<a href="telnet://goya.its.rpi.edu">Telnet Link to "goya"</a>

Here's a "gopher" link : Gopher Link to Library of Congress

Here's a "telnet" link : Telnet Link to "goya"