How to create a printable Twitter-Bootstrap page

Bootstrap 3.2 update: (current release)

Current stable Bootstrap version is 3.2.0.
With version 3.2 visible-print deprecated, so you should use like this:

Class                        Browser    Print
 -------------------------------------------------
.visible-print-block         Hidden        Visible (as block)
.visible-print-inline        Hidden        Visible (as inline)
.visible-print-inline-block  Hidden        Visible (as inline-block)
.hidden-print                Visible       Hidden

Bootstrap 3 update:

Print classes are now in documents: http://getbootstrap.com/css/#responsive-utilities-print

Similar to the regular responsive classes,
       use these for toggling content for print.

Class            Browser    Print
 ----------------------------------------
.visible-print   Hidden     Visible
.hidden-print    Visible    Hidden

Bootstrap 2.3.1 version:

After adding bootstrap.css file into your HTML,
Find the parts that you don't want to print and add hidden-print class into tags. Because css file includes this:

@media print {
  .visible-print  { display: inherit !important; }
  .hidden-print   { display: none !important; }
}

Be sure to have a stylesheet assigned for printing.
It could be a separate stylesheet:

<link rel="stylesheet" type="text/css" media="print" href="print.css">

or one you share for all devices:

<link rel="stylesheet" type="text/css" href="bootstrap.min.css"> # Note there's no media attribute

Then, you can write your styles for printers in the separate stylesheets or in the shared one using media queries:

@media print {
    /* Your styles here */
}