How to gather data from a website (without RSS) and post to an other site

I was wondering what could be used to collect something like a text with an identifier on a page, such as:

<span id="text">Text I'm interested to grab</span>

And copy that on an other page. Unfortunately the site I want to collect data from hasn't got an API or an RSS feed, which I guess would have made the job a lot easier. It would be awesome if someone could advise me on what should I use to achive my objective.