This post stems from the discussion going over at Freshblog regarding how to make posts printable. The method being suggested there is a little bulky and seems a little slow for my liking, so I set to out to write my own bit of code, which now I'll explain to you. This method makes use of external stylesheets, which brings down page load times, as well as lines of code to execute for the script! :) So here it is.

Start off by making all your stylesheets external. It might take a while, or it might take one cut-paste, its upto your template. Now, link to them by using the <link> tags. The syntax for the tag is as follows:

<link rel="[1]" type="text/css" title="[2]" href="[3]">

where:

[1]: either stylesheet or alternate stylesheet. The one holding the stylesheet value will be the default stylesheet.
[2]: the title of your stylesheet so that it can be called from the script.
[3]: the path to your stylesheet.

Now, put in this function in the head part of your template within <script></script> tags:

function change_css(title) {
   var i, a = document.getElementsByTagName("link"), b;
   for(i=0;i<a.length;i++) {
     if(a[i].getAttribute("rel").indexOf("style") != -1 && a[i].getAttribute("title")) {
       a[i].disabled = true;
       if(a[i].getAttribute("title") == title) a[i].disabled = false;
     }
   }
}

There! You're done with the hard part! Now, all you have to do is make links which will load in the different stylesheets! The link will look like this:

<a href="javascript:change_css('[4]')">Link Text</a>

where:

[4]: the title of the stylesheet you want to load.

Hence, if there is a <link> tag with the title set to "Print" (for a printer friendly look), your link will look like this:

<a href="javascript:change_css('Print')">Print This</a>

Remember! The stylesheet is applied to the whole page. So if that link is executed on the main page, your entire main page will get styled accordingly. I'd suggest making those links appear only on your post pages using Blogger conditional tags. I don't know who might want to print out a while main page anyway :P

Simple? Good! This method can be used for many other things. In case you want to make several stylesheets for your viewers to pick from, the same method can be used. Let your imagination run wild! :)