Yes, Issuu is very similar to Scribd.
I think what you are wishing for is a more developed PDF viewer module for wikidot. And of course a bulk uploader would be very useful.
Scribd iPaper
You can embed Scribd ipaper into your wiki in the usual way. From the Embed menu select the code:
and put it inside html body tags as shown below. Then add an iframe to refer to the number of the codeblock on your page. In my example below it is the second block of html on my page, hence the /code/2.
[!--
[[code type="html"]]
<html>
<head>
<title>Scribd iPaper</title>
</head>
<body>
<object codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" id="doc_796610732017931" name="doc_796610732017931" classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" align="middle" height="250" width="80%"> <param name="movie" value="http://d.scribd.com/ScribdViewer.swf?document_id=5890405&access_key=key-1y51ud1jbyofdfrqp7gv&page=1&version=1&viewMode=list"> <param name="quality" value="high"> <param name="play" value="true"> <param name="loop" value="true"> <param name="scale" value="showall"> <param name="wmode" value="opaque"> <param name="devicefont" value="false"> <param name="bgcolor" value="#ffffff"> <param name="menu" value="true"> <param name="allowFullScreen" value="true"> <param name="allowScriptAccess" value="always"> <param name="salign" value=""> <param name="mode" value="list"> <embed src="http://d.scribd.com/ScribdViewer.swf?document_id=5890405&access_key=key-1y51ud1jbyofdfrqp7gv&page=1&version=1&viewMode=list" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" play="true" loop="true" scale="showall" wmode="opaque" devicefont="false" bgcolor="#ffffff" name="doc_796610732017931_object" menu="true" allowfullscreen="true" allowscriptaccess="always" salign="" type="application/x-shockwave-flash" align="middle" mode="list" height="250" width="80%"></embed> </object> <div style="margin: 6px auto 3px auto; font-family: Helvetica,Arial,Sans-serif; font-style: normal; font-variant: normal; font-weight: normal; font-size: 12px; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; display: block;"> <a href="http://www.scribd.com/upload" style="text-decoration: underline;">Publish at Scribd</a> or <a href="http://www.scribd.com/browse" style="text-decoration: underline;">explore</a> others: <a href="http://www.scribd.com/browse/Academic-Work/?style=text-decoration%3A+underline%3B">Academic Work</a> <a href="http://www.scribd.com/tag/tool" style="text-decoration: underline;">tool</a> <a href="http://www.scribd.com/tag/collaboration" style="text-decoration: underline;">collaboration</a> </div>
</body>
</html>
[[/code]]
--]
[[iframe http://strathviewconsultants.wikidot.com/support:sandbox/code/2 frameborder="0" scrolling="no" width="80%" height="250px"]]
This gives the result below (I've reduced the size to take up less screen real estate):
Rob