I recently downloaded Picasa and have been having enormous fun playing around with it.  Picasa is part of Google and didn't turn my computer all wonky or give me a virus or give me the dreaded blue screen of death.  It went rather smoothly, once I figured out that it was on my desktop and not in an internet tab.

I made the banner for my blog in Picasa.  I followed this tutorial and was pleased to learn how simple it really is.

I have also discovered that with the collage feature I can also make these...

I am so thoroughly impressed!  Picassa also imported all my pictures from my blog, so I didn't tediously have to transfer everything over.