Best code for alert algorithm

I'm not even sure if I'm in the right section -- I know Jython but I'm a complete newb compared to most of you guys but I had a general question that I'm sure you guys can answer.

I was wondering what programming language would be best for building code that would have the ability to look at a set of specific webpages and alert me via email instantaneously anytime a certain posting was made that reached a certain threshold or fit certain requirements.

Thanks in advance.