Two other tools do similar things too:
- Datawi.re, by Annabel Church 
- Stream Tools, by the NYT 
Data journalism is very sexy! Unfortunately it's still very hard to find that story needle, and increasingly so when you open up the data aperture.
Nice job but why do you require postfix?!
You should be using either sendmail/mailx or a custom user/password SMTPD server (e.g. google's smtpd).
To actually send the mails, we use the aptly named 'nodemailer' module, with the 'smtp' transport mechanism, which also relies on a running SMTP server. (btw, one can use a 'sendmail' transport mechanism).
Also, you should host a demo somewhere.
Re: Google Alerts - you're right... to a certain extent. Here, you can mash up datasets, compile them, tweak them, THEN and only then compare them to parameters you set. Alerts++, then.
Here is a screenshot of the alerts I received this morning: http://imgur.com/vG0PqDf
The alert was set for London Euston area.
I will add an issue to the repo because, as you see, the styling is not very pretty - and the wording is far from eloquent!
Especially the install.sh only works on Linux.
Otherwise very cool idea :-)
I have hard time reconciling:
"Don't know how to code? That's fine."
"The code is available on Github, and that's where you should start. Just clone the repo and run the installation script located at root."
I think you seriously overestimate the layman's abilities here. Is this for programming laymen? Github is one of the last things people learn, for better or worse.
Intriguing, nonetheless. Will follow.
Feel free to contribute :)
Cron wouldn't work on Windows either, by the way.
To have a look at some snippets, I would recommend going through the wizard, then cracking open one of the examples. The plumbing is a bit overly-complicated, though, I am sure there is a way to make queries in a simpler way.