This is the code for a simple RSS Reader. It is based on [David Gravereaux]'s code (at [TclHttpd RSS Processing]) and splitted in 
a library to do the real reading and a GUI frontend.

----
   package provide czrss 0.1

   package require snit
   package require tdom
   package require http

   snit::type ::czrss::doc {
    variable xpath
    variable channel
    variable items
    variable url

    # Konstruktor für eine bestehende URI
    constructor { uri } {
	puts stdout "rss::doc $uri"
	
	set url $uri
	$self load
    }

    method load { } {
	# load xml to temporary file
	set file "[ clock seconds].xml"
	set out [ open $file w ]
	http::geturl $url -channel $out
	close $out

	# load xml into dom from temporary file
	set doc [ dom parse -channel [tDOM::xmlOpenFile $file] ]
	set _root [ $doc documentElement ]
	file delete $file
	
	set root [$doc documentElement]	
	switch [getRSSVersion $doc] {
	    0.91 - 0.92 - 0.93 - 2.0 {
		set xpath(titleXpath)	{/rss/channel/title/text()}
		set xpath(linkXpath)	{/rss/channel/link/text()}
		set xpath(imgNodeXpath)	{/rss/channel/image/title}
		set xpath(imgTitleXpath	{/rss/channel/image/title/text()}
	        set xpath(imgLinkXpath)	{/rss/channel/image/url/text()}
  	        set xpath(imgWidthXpath)	{/rss/channel/image/width/text()}
	        set xpath(imgHeightXpath) {/rss/channel/image/height/text()}
		set xpath(storiesXpath)	{/rss/channel/item}
		set xpath(itemTitleXpath)	{title/text()}
		set xpath(itemLinkXpath)	{link/text()}
		set xpath(itemPubDateXpath)	{pubDate/text()}
		set xpath(itemDescXpath)	{description/text()}
	    }
	    1.0 {
		set xpath(titleXpath)	{/rdf:RDF/*[local-name()='channel']/*[local-name()='title']/text()}
		set xpath(linkXpath)	{/rdf:RDF/*[local-name()='channel']/*[local-name()='link']/text()}
		set xpath(imgNodeXpath)	{/rdf:RDF/*[local-name()='image']}
		set xpath(imgTitleXpath) {/rdf:RDF/*[local-name()='image']/*[local-name()='title']/text()}
		set xpath(imgLinkXpath)	{/rdf:RDF/*[local-name()='image']/*[local-name()='url']/text()}
		set xpath(imgWidthXpath) {/rdf:RDF/*[local-name()='image']/*[local-name()='width']/text()}
		set xpath(imgHeightXpath) {/rdf:RDF/*[local-name()='image']/*[local-name()='height']/text()}
		set xpath(storiesXpath)	{/rdf:RDF/*[local-name()='item']}
		set xpath(itemTitleXpath)	{*[local-name()='title']/text()}
		set xpath(itemLinkXpath)	{*[local-name()='link']/text()}
		set xpath(itemPubDateXpath)	{*[local-name()='pubDate']/text()}
		set xpath(itemDescXpath)	{*[local-name()='description']/text()}

	    }
            default {
		error "Unssupported schema [getRSSVersion $doc]"
	    }
	}

	# Channel
	set cN [ $_root child 1 channel ]
	set channel [::czrss::channel create %AUTO% $self $cN]
	puts $channel

	# Nachrichten
	set items {}
	set stories [$_root selectNodes $xpath(storiesXpath) ]
	foreach iN $stories {
	    lappend items [ ::czrss::item  create %AUTO% $self $iN ]
	}
    }


    method xpath { key } {
	return $xpath($key)
    }	

    method channel {} {
	return $channel
    }

    method items {} {
        return $items
    }	

    proc getRSSVersion {doc} {
	set root [$doc documentElement]
	switch [$root nodeName] {
	    rss {
		if {[$root hasAttribute version]} {
		    return [$root getAttribute version]
		}
		# Best guess as most stuff is optional...
		return 0.92
	    }
	    rdf:RDF {
		return 1.0
	    }
	    default {
		return 0
	    }
	}
    }
    }

    snit::type ::czrss::item {
    variable _node
    variable _doc

    constructor {doc node } {
	variable history
	set _doc $doc
	set _node $node
    }

    method title { } {
	set xpath [$_doc xpath itemTitleXpath]
	return [ ::czrss::nodeTxt $_node $xpath]
    }

    method link {} {
	set xpath [$_doc xpath itemLinkXpath]
	return [ ::czrss::nodeUri $_node $xpath]
    }
    
    method description {} {
	set xpath [$_doc xpath itemDescXpath]
	return [ ::czrss::nodeTxt $_node $xpath]
    }
	
    method pubDate {} {
	set xpath [$_doc xpath itemPubDateXpath]
	return [ ::czrss::nodeTxt $_node $xpath]
    }
    }


    snit::type ::czrss::channel {
    variable _doc
    variable _root
    
    constructor { doc root} {
	set _doc $doc
	set _root $root
    }

    method title { } {
	set xpath [$_doc xpath titleXpath]
	return [ ::czrss::nodeTxt $_root $xpath]
    }

    method imgLink {} {
	set xpath [$_doc xpath imgLinkXpath]
	return [ ::czrss::nodeUri $_root $xpath]
    }
	
    method imgTitle {} {
	set xpath [$_doc xpath imgTitleXpath]
	return [ ::czrss::nodeUri $_root $xpath]
    }
    
    method imgWidth {} {
	set xpath [$_doc xpath imgWidthXpath]
	return [ ::czrss::nodeTxt $_root $xpath]
    }

    method imgHeight {} {
	set xpath [$_doc xpath imgHeightXpath]
	return [ ::czrss::nodeTxt $_root $xpath]
    }
    }


    namespace eval ::czrss {

    proc encUri {uri} {
	return [string map { & %26 } $uri]
    }

    proc encTxt {txt} {
	return [string map { & &amp; < &lt; > &gt; } $txt]
    }

    proc nodeUri {node xpath} {
	if {[$node selectNode $xpath] != ""} {
	    # Only if there is a lonely &, quote it back to an entity.
	    return [encUri [[$node selectNode $xpath] nodeValue]]
	} else {
	    return ""
	}
    }

    proc nodeTxt {node xpath} {
	if {[$node selectNode $xpath] != ""} {
	    return [[$node selectNode $xpath] nodeValue]
	} else {
	    return ""
	}
    }
   }