those Gif format files were very famous back on the on the early 90's. it was the only format that could animate a picture sequence.
Now we use mostly flash format files for web animations, however these gif files started popping up again on the net. the files now are used in very different ways, from art to wedding photography. I think that it is because all the mobile devices that can't ready flash format.
I tried doing my own:
Also check these wedding (gif) photography