One potentially interesting use of the AccessHandler module is to protect an Apache Proxy configuration. For example, after installing and enabling mod_proxy, mod_proxy_http, and mod_proxy_html you could proxy websites like so:

<Location /proxy/>
    # Base "Rewrite URLs" configuration
    ProxyHTMLLinks  a       href
    ProxyHTMLLinks  area        href
    ProxyHTMLLinks  link        href
    ProxyHTMLLinks  img     src longdesc usemap
    ProxyHTMLLinks  object      classid codebase data usemap
    ProxyHTMLLinks  q       cite
    ProxyHTMLLinks  blockquote  cite
    ProxyHTMLLinks  ins     cite
    ProxyHTMLLinks  del     cite
    ProxyHTMLLinks  form        action
    ProxyHTMLLinks  input       src usemap
    ProxyHTMLLinks  head        profile
    ProxyHTMLLinks  base        href
    ProxyHTMLLinks  script      src for

    # To support scripting events (with ProxyHTMLExtended On)
    ProxyHTMLEvents onclick ondblclick onmousedown onmouseup \
            onmouseover onmousemove onmouseout onkeypress \
            onkeydown onkeyup onfocus onblur onload \
            onunload onsubmit onreset onselect onchange

    # Limit all Proxy connections to authenticated sessions by default
    PerlAccessHandler OpenILS::WWW::AccessHandler

    # Strip out Evergreen cookies before sending to remote server
    RequestHeader edit Cookie "^(.*?)ses=.*?(?:$|;)(.*)$" $1$2
    RequestHeader edit Cookie "^(.*?)eg_loggedin=.*?(?:$|;)(.*)$" $1$2
</Location>

<Location /proxy/example/>
    # Proxy example.net
    ProxyPass http://www.example.net/
    ProxyPassReverse http://www.example.net/
    ProxyPassReverseCookieDomain example.net example.com
    ProxyPassReverseCookiePath / /proxy/example/

    ProxyHTMLEnable On
    ProxyHTMLURLMap http://www.example.net/ /proxy/example/
    ProxyHTMLURLMap / /proxy/mail/
    ProxyHTMLCharsetOut *

    # Limit to BR1 and BR3 users
    PerlSetVar OILSAccessHandlerHomeOU "BR1,BR3"
</Location>

As mentioned above, this can be used for multiple reasons. In addition to websites such as online databases for patron use you may wish to proxy software for staff or patron use to make it appear on your catalog domain, or perhaps to keep from needing to open extra ports in a firewall.