Just sending a file as an HTML-formatted email is surprisingly hard to do (i.e. you can't type raw HTML into your email client and have it render in the recipient's inbox.)
So I put a script together to do it - https://gist.github.com/4176850
It requires Python (it's a Python script), but runs from the command line, thus:
$ python send_html_email.py --filename='test_file.html' --email@example.com
It runs through Gmail's SMTP service, so you will need a Gmail account - and you'll be prompted for your email and password when you run the script.
Feel free to use, feedback, fork, etc.
I have recently come across the service mailtrap (mailtrap.io), which is a brilliant companion to this sort of solution. Mailtrap operates an SMTP service that doesn't go anywhere. Sound crazy, but it's great - you set up an account, get a set of SMTP credentials, and then everything you send to that server gets parked in the Mailtrap inbox - where you can see the emails received as HTML, plain text and even source. Try it out.