If a report or a book that is cited (using the cite) command is available (or there is information about it) on WorldWide Web then it is possible to add the appropriate hypertext links in your bibliographic database (the .bib) file.
Here is an example of a bibliographic entry for the original LaTeX[1] book:
@book{lamp:latex,
title = "LATEX User's Guide \& Reference Manual",
year = 1986 ,
author = "Leslie Lamport",
Publisher = "Addison-Wesley Publishing Company, Inc.",
note = "Online information on TeX and LaTeX is available at
\htmladdnormallink{http://curia.ucc.ie/info/TeX/menu.html}
{http://curia.ucc.ie/info/TeX/menu.html} and
\htmladdnormallink{http://es-sun2.fernuni-hagen.de/info2html?(latex.info)Top}
{http://es-sun2.fernuni-hagen.de/info2html?(latex.info)Top}"}
No other modifications are required for this to work - LaTeX and BibTeX should work as normal.
For those who use the Harvard style for references there exists a special conversion add-on package.