Ashish has already written about Shape Collage, which is an awesome desktop application to create Collage from your photos available on your local storage. Now, Shape Collage has introduced the online version, Shape Collage Online.
All you need to do is, give the URLs (one URL per line) or you can give a URL of particular set of photos from Flickr, Facebook, Picasa, Photobucket etc. You can also make collages using Google image search etc.
Later you need to choose the layout.
And hit the ‘Create’ button and soon the Collage will appear in front of you.
Here you get the direct URL link and Embed code for this collage, also clicking on any photo allows you to see the original photo (i.e. wherever it is hosted).
Shape Collage online doesn’t allow you to create collages using the photos from local storage, if you want to add photos from your local storage, you need to use the desktop application i.e. Shape Collage.