OK,

Your first step would be to open the account for that at.....Google (quite obviously):

Sign up for the Google AJAX Feed API

You will get a very very long key number. keep it in a safe place! (just kidding.)

Now copy and paste that code into your ascx file. I was just putting it under the dnn tags.:

<script type="text/javascript" src="http://www.google.com/jsapi?key=YOUR-API-KEY">
</script>

<script type="text/javascript" src="rssdisplayer.js"></script>

Now in the place where you would like to add the RSS put that code: (change to source mode.)

<script type="text/javascript">

//USAGE SYNTAX: new rssdisplayer("divid", "rssurl", numberofitems, "displayoptions")
new rssdisplayer("nameofdiv", "http://www.yourdomain.com/.xml", 4, "date, description")

</script>

And see how it works.

For more info look here:

A robust RSS Feed displayer

In both templates where I was implementing it, all that was left now was to make the Url of the RSS be changed dynamically by the user who is submitting the link or profile.

For that we have replaced the url with a custom field:

new rssdisplayer("nameofdiv", "[CUSTOM:rss_url]", 4, "date, description")

That's it!

Writing that article made me look once again at :

Google Ajax feed api blog

And to find out that they have developed new features which are really interesting for coming templates!

Good luck!