First, they have X11 listed incorrectly as a PPC app. If you have an Intel based Mac then the installation CDs includes a pkg of X11 as a Universal app.

Once you have X11 installed then you can also get ...

1) Inkscape (Universal) ... for all of your SVG editing needs.

2) Gimp (Universal) ... for all of your raster image editing needs.

... and I am surprised that they left Eclipse off of the list. While Xcode is preferred for doing OS X development, it is still worth a mention :-)

I'm sure there are others, but these are the ones I use most.