[updated] Uses the lastRSS library to
aggregate RSS feeds.
lastRSS (and this plugin) gives you:

• All RSS versions supported (0.9, 1.0 and 2.0)
• Regullar expression parsing (very quick)
• Returns an associative array with RSS fields
• RSS tags not present in RSS are also not present in result now
• Transparent cache
• Character encoding conversion (all encodings supported by iconv library)

lastRSS is free open-source software (GNU/GPL), this plugin has a BSD license

Instructions:

1. Create the cache directory – wp-content/aggrss-cache – and make it world writeable (chmod 777)
2. create subdir wp-content/plugins/lastRSS
3. Extract lastRSS.zip and save lastRSS.php in wp-content/plugins/lastRSS
   local copy: lastRSS.0.9.1.zip (2.9 KiB, 2,636 downloads)
4. Save aggrss.php.txt (4.4 KiB, 2,483 downloads) as aggrss.php in your wp-content/plugins directory
5. Activate the plugin from the Plugins page (re-activate (deactivate + activate) if you are upgrading aggrss)

Use:

$rs = aggrss($rssurl,$striptags=false,$num=0);
/*
$rssurl, url to the rss

optional parameters:
$striptags, if true all html tags will be remove from decriptions.
$num, defines the number of records you want to display, $num=0 equals all available
*/

aggrss returns the rss content as an associative array with RSS fields, see sample below.

if ($rs = aggrss('http://soderlind.no/feed/rss2/')) {
    // dump the structure
    //echo "<pre>";
    //print_r($rs);
    //echo "</pre>";
    echo "<h2><a xhref='" . $rs[link] . "'>" . $rs[title] . "</a></h2>";
    echo $rs[description] . "<br />";

    foreach ($rs['items'] as $item) {
        echo "<p><a xhref='" .$item['link']. "'>" . $item['title'] . "</a><br />" .html_entity_decode($item['description']). "</p>";
    }

    if ($rs['items_count'] < = 0) {
        echo "Sorry, no items found in the RSS file  "; }
    } else {
        echo "<!-- It's not possible to reach RSS file -->";
    }
}

Demo:
http://soderlind.no/dilbert/