While working on a requirement where we wanted to display calendar of the assigned user, we thought of getting the calendar displayed within an IFRAME.

We were able to display the calendar within the iframe, but the iframe displayed the page with the headers and sidebars which looked very bad and took up a lot of screen space. After a lot of searches and head banging came up with a very simple solution.

All you need to do is to add ?isdtp=mn to your url.

Note: This is not a supported by salesforce so you need to use it at your own risk. There are a few other options for this parameter and  ‏@ca_peterson has explained this in his blog http://www.ca-peterson.com/2011/11/magic-isdtp-param.html