Skin Manager

Skin Manager (previously known as Skin Finder) allows you to open a Minecraft skin from a Minecraft username or URL. From there, you can save it to your computer, set it as your Minecraft skin, or save it to your mobile device for use with Minecraft: Pocket Edition. It's fast and easy!

You can put Skin Manager on your own website, just copy and paste the HTML code below to your site (it's just like embedding a YouTube video):

<iframe src="" style="width: 100%; height: 470px; border: 0px;"></iframe>

More info is available at it's GitHub page.