You probably didn't even know there was a PFRE sky library did you. Yes, since March of 2006 there has been one. Many readers over the years have donated public domain skies for everyone to use and even though I haven't had a link to the old the free sky library on the blog for a while now anyone that did a search for free skies would find it.
About a month ago Karl Hoelscher of Phoenix sent me four new Arizona skies and a few days ago Karl Inge Punsvik, of Narvik Norway sent me some Norwegian skies. Before this current update I did the HTML for the sky library by hand. But since the update consists of 92 new skies I needed to automate the updating of the library so I used the Lightroom 3 HTML slideshow that automatically generates a slide show with thumbnails and multiple pages.
You can now browse through the library, decide which sky you want, then click on the thumbnail to display the full-size photo and then right click and select "Save Image as..." to download the sky.
For those that need help using these skies to replace the sky in your photo see the pasttutorials on PFRE on the subject of sky replacement. Here is a list of some of the video tutorials we featured in the past:
Oh yea, I've added a link to the new sky library on the right side-bar under "Other Links".