This is a nice interactive visualization of the top 50 White House Petitions in tabular, map, and graph form. You can sort by most popular, greatest average signature gain, and male/female ratio.

http://roadtolarissa.com/whitehouse/

The top 5 have sharp spikes in Nov / Dec 2012. Here is some analysis of the Texas Secession Petition: http://www.unc.edu/~ncaren/secessionists/daybyday.html and