I finally got around to kicking the tires of my "virtual tarball" idea, which is basically an XML document that consists of HTML-renderable <ul> / <li> tags that describe the contents of an Internet-based directory structure. This allows a single URL to be used to fetch an entire set of files by using a single list of hyperlinks.

I prototyped this on the server side at cachefile.net using a REST-like approach. Basically, one would simply need to append the path of a known cached directory at cachefile.net to the following URL:

http://cachefile.net/svc/mrr/ [+ known path from root]

For example:

http://cachefile.net/svc/mrr/scripts/OpenAjax/

This would output the contents of the directory at http://cachefile.net/scripts/OpenAjax/ in XML / <li> format, with hyperlinks.

<div class="mrr">
    <label>
        Index of <span class="mrrbase">http://cachefile.net/scripts/OpenAjax/</span>
    </label>
    <ul class="mrrparent">
        <li>
            <a href="../">Parent</a>
        </li>
    </ul>
    <!--
        This is a mrr ("mirror") file, also a.k.a. a "virtual tarball".
        For more information, see http://www.jondavis.net/blog/?tag=/virtual%20tarball
        -->
    <ul class="mrrdirlist">
        <li class="mrrdir">
            <a href="hub">hub</a>
            <ul class="mrrdirlist">
                <li class="mrrdir">
                    <a href="hub/0.6">0.6</a>
                    <ul class="mrrdirlist">
                        <li class="mrrdir">
                            <a href="hub/0.6/release">release</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/0.6/release/OpenAjax.js">OpenAjax.js</a>
                                </li>
                            </ul>
                        </li>
                        <li class="mrrdir">
                            <a href="hub/0.6/src">src</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/0.6/src/OpenAjax.js">OpenAjax.js</a>
                                </li>
                            </ul>
                        </li>
                        <li class="mrrdir">
                            <a href="hub/0.6/testsrc">testsrc</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/0.6/testsrc/TestSuite.html">TestSuite.html</a>
                                </li>
 
                              <!-- .... -->

                            </ul>
                        </li>
                        <li class="mrrfile">
                            <a href="hub/0.6/build.xml">build.xml</a>
                        </li>
                        <li class="mrrfile">
                            <a href="hub/0.6/index.html">index.html</a>
                        </li>
                    </ul>
                </li>
                <li class="mrrdir">
                    <a href="hub/1.0_build117">1.0_build117</a>
                    <ul class="mrrdirlist">
                        <li class="mrrdir">
                            <a href="hub/1.0_build117/release">release</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/1.0_build117/release/OpenAjax.js">OpenAjax.js</a>
                                </li>
                            </ul>
                        </li>
                        <li class="mrrdir">
                            <a href="hub/1.0_build117/src">src</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/1.0_build117/src/OpenAjax.js">OpenAjax.js</a>
                                </li>
                            </ul>
                        </li>
                        <li class="mrrdir">
                            <a href="hub/1.0_build117/testsrc">testsrc</a>
                            <ul class="mrrdirlist">
                                <li class="mrrfile">
                                    <a href="hub/1.0_build117/testsrc/TestSuite.html">TestSuite.html</a>
                                </li>
                                  <!-- ... -->
                            </ul>
                        </li>
                        <li class="mrrfile">
                            <a href="hub/1.0_build117/build.xml">build.xml</a>
                        </li>
                        <li class="mrrfile">
                            <a href="hub/1.0_build117/index.html">index.html</a>
                        </li>
                    </ul>
                </li>
                <li class="mrrfile">
                    <a href="hub/home.href">home.href</a>
                </li>
            </ul>
        </li>
        <li class="mrrfile">
            <a href="home.href">home.href</a>
        </li>
    </ul>
</div>

As an added bonus, you can also get HTML wrapping of the XML file by appending the querystring, "?format=html".

http://cachefile.net/svc/mrr/scripts/OpenAjax/?format=html (click to view) 

You can let your imagination take you wherever you want to go as to what you would do with such a tool from here. I'm opening the uncommented server-side source code for this. The PHP file for my proprietary implementation is here: http://www.jondavis.net/misc/cachefile_mrr_gen.txt

Unfortunately, I have a sinking feeling that this opens up security vulnerabilities. If anyone can spot any, please let me know. I already filter out "..".