I recently released GvGen 0.9, a python class that generates dot. I added a smart mode that you can activate on your instance:

>>> graph = gvgen.GvGen()
>>> graph.smart_mode = 1

Then, when you perform multiple links such as:

>>> graph.newLink(ip1, target)
>>> graph.newLink(ip1, target)
>>> graph.newLink(ip1, target)

The link line size and arrow will be biger, such as: smartmode-1.png

Or, if you have both direction links

>>> graph.newLink(ip1, target)
>>> graph.newLink(target, ip1)

You will obtain: smartmode-2.png

Download the tarball now!