I didn’t use the API (not that technically inclined). I exported my contacts into a CSV file and then formatted it for ManyEyes. I just created a frequency table with the firms my contacts worked. I had to normalize the firm names (since people entered them differently in some cases), but otherwise it didn’t take too much to scrub the data for this viz. I am thinking of updating this post and the viz to look at how my network has changed over the last year.