It's a well know fact that running X11 applications on ae Mac crates a lot of ugliness. I discovered a way to solve this, at least partially.
A lot of Unix applications use the Gimp Tool Kit, or GTK for short. You can install GTK on Mac via MacPorts by running sudo port install gtk2 in Terminal. There are some themes in MacPorts as well to make your app look like an Air app instead of Win95; they work, but the look is still alien.
However, there is a GTK theme called mac4lin that emulates the Mac look on Linux, but I discovered this can be used on the Mac as well. Download and extract mac4lin and extract and copy one of the archives in the GTK folder to /opt/local/share/themes. Then run gtk-chtheme from MacPorts to change to your new aqua theme. As a final step, click the Font button to set the font to Lucida Grande 10pt, and you're done.
Detailed instructions and screenshots can be found on my blog.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20100410105751461