If you want an open source alternative to Photoshop or Photoshop Elements, try the following three offerings:

Paint.net is a free program available at (http://www.getpaint.net/index.html). It offers
the use of layers and quite a number of effects, and in my experience is easier for
the novice user than Photoshop or the GIMP while still providing all the image
manipulation options the average user require.

The GIMP (http://www.gimp.org/), while also free, is far more complex. It offers more
options but is much intuitive to use. This is a good Photoshop substitute for those
doing serious graphic manipulation, but it does have a bit of a learning curve.

For simple editing and resizing, try the free (donation-ware) program Irfanview
(http://www.irfanview.com/). Irfanview is also very handy when one needs to print
out images, as it offers several print options, including resizing on the fly and dynamic
preview.

Open Source Libraries:
http://www.virtuallrc.com/

Open Source for Kids:
http://www.kidsnetsoft.com/html/open.html
Open Source: Web 2.0 for kids:
http://www.kidsnetsoft.com/html/web20.html

If you know of any others, please let me know.