Announcing the Bootswatchlet. This bookmarklet makes it quick and easy for you to apply different swatches to yours or someone else’s Bootstrap page.

Installation

Scroll down to the bottom of the Bootswatch homepage. Drag the “Bootswatchlet” link to your bookmarks bar.

Usage

While on a Bootstrap page, click the bookmarklet in your bookmarks bar to activate a random theme. A dropdown menu appears in the top-right corner where you can specify another theme. Click the bookmarklet again to toggle it off.

Try it out on the current page, Twitter Bootstrap’s demo page, or any other page built with Bootstrap.

Caveats

The bookmarklet won’t work perfectly with bootstrap-responsive.css, since it appends the stylesheets after it.

For pages that are heavily customized and use Bootstrap more as an underlying framework than a theme, a lot of the swatch styles will be overridden.

There’s no substitute for attentive design tailored to the content, even when using a theme. This bookmarklet is meant to give you a rough feel for how the page would look with a particular theme, not the optimal look.

Source

If you’re interested, you can check out the gist for the bookmarklet.