Inkscape, release 0.42
Another tool that open source community can be proud: INKSCAPE
Inkscape is an open source drawing tool with capabilities similar to Illustrator, Freehand, and CorelDraw that uses the W3C standard scalable vector graphics format (SVG). Some supported SVG features include basic shapes, paths, text, markers, clones, alpha blending, transforms, gradients, and grouping. In addition, Inkscape supports Creative Commons meta-data, node-editing, layers, complex path operations, text-on-path, and SVG XML editing. It also imports several formats like EPS, Postscript, JPEG, PNG, BMP, and TIFF and exports PNG as well as multiple vector-based formats.
Inkscape’s main motivation is to provide the Open Source community with a fully W3C compliant XML, SVG, and CSS2 drawing tool. Additional planned work includes conversion of the codebase from C/Gtk to C++/Gtkmm, emphasizing a lightweight core with powerful features added through an extension mechanism, and the establishment of a friendly, open, community-oriented development process.
To be convinced by the quality of operations performed by inkscape, a look at the screenshots section is invaluable. As usual in the open soure world, the code has been made to be highly portable, understand that inkscape is available for download for #Linux, MacOsx and windows…
For any "Bitmap only" operations on pictures files, I recommend to use the complementary open source Tool GIMP