Inkscape

Inkscape is an open source vector graphics editing application, with capabilities similar to Illustrator and CorelDraw.

Vector graphics are often used for illustrations, graphic design or advanced work with graphical text. Inkscape is a perfect tool for creating beautiful complex or simple images, flyers or posters where the more block-orientated layout of print applications is not appropirate. Some of more advanced uses of Photoshop – like applying effects to fonts and altering the shape of images – are best done in Inkscape rather than GIMP.

Creating high quality and detailed images, diagrams and other graphics for print or the internet
Creating interactive slideshows for presentations or the internet

Very powerful vector image editor with many applications
Inkscape has a good user and developer community

It could be difficult to pick up all the skills needed to complete a project

Windows, Mac OSX, Linux
FOSS
Easy

Adobe Illustrator
CorelDraw