Inkscape is a free vector graphics editor which can act as a replacement for Adobe Illustrator. Inkscape has many advanced tools needed for graphic designers to create Scalable Vector Graphics (SVG) files. It can be used to create print media, websites and banners.
GIMP is a popular free alternative to Adobe Photoshop. Although it is not as full featured and powerful as Photoshop it is handy for basic photo editing. It can be used to remove backgrounds, add filters, change contrast and brightness and has many other features.
Picasa is an excellent photo viewer from Google. Picasa allows home users to present photos in collages and movies, perfect for displaying photos after a big event. Picasa is useful to organise photos in a simple and searchable database and allows one-click edits with effects and tuning features.