A few months ago, I went through a few of the ways you can visualize your inbox, fo' free. The methods I discussed can give you a fairly detailed portrait of your inbox's interactions and vocabulary, but the visualizations themselves are quite basic. There are, however, a number of projects that take more creative approaches to email visualization. Many of them are, alas, one-offs (and many more are manifested only in research papers). 

Email visualization tools you can use: 

1.  Anymails

  • Anymails employs metaphor, here with species representing types of email (family&friends, school, commerce, spam etc) and single animals (which look more like bacteria to me) representing each email received. The email's state is represented by the speed and hairiness of its animal: unread mail is hairy and pulses quickly; read mail is less hairy and pulses slowly, and responded mail is hairless and barely moves. The default inbox view shows all recent mail (past day, week, or month) swimming across the screen, but users can filter by species and status, and can scroll back to see how their inboxes looked in previous months. 
  • Made by: Carolin Horn and Florian Jenett

2. Gmail Meter

  • The most straightforward (and plainest) of the bunch, Gmail Meter analyzes your Gmail and sends you a weekly chart-based activity report. Some of stats include hourly and weekly volume of email, top senders and recipients, thread length, and average response time. Gmail Meter also tells you how efficient you are given the number of emails in your inbox, archives, labels, and trash, and lets you compare internal and external email behaviors.
  • Made by: ShuttleCloud

3. Calendar Analytics Add-in Tool 

  • Calendar Analytics analyzes your Exchange calendar and presents the data in a Power Pivot dashboard in Excel. Note: fewer words are more poetic than "Power Pivot dashboard in Excel." Some of the data presented include past and future meeting breakdown by topic and person, so you can see just how often you've been meeting with Ned from Accounting about the annual Kitty Ball. 
  • Made by: Microsoft

4. Luminoso

  • Simply put, this MIT Media Lab hatchling understands language- subtext, slang, allusions, sarcasm and all. Put it to work on emails, and it can divine subjects, sentiment, and birds of a feather, and gussy up this information in network visualizations. 
  • Made by: Dr. Catherine Havasi, Rob Speer, Jason Alonso, Dennis Clark, and Ken Arnold

Email Analytics Tools You Can't Use, but Can Look at

1. Mailgarden

  • Mail Garden also employs metaphor in its inbox visualization--each inbox is a forest made up of single email trees. The longer the email, the taller the tree. 
  • Made by: Kjen Wilkens, Damian Stewart, Jenny Cahier, and Marcela Machuca.  

2. My Map

  • My Map visualizes the relationships between Christopher Baker and his contacts from 1998 up to the present. Relationship data comes from the To, From, and CC fields of per 60,000 of Baker's emails. Baker's top contacts are visualized in a circular network graph, with their communication rank, emails sent, and date last contacted displayed in a mouseover. The intensity of a given relationship is denoted by line weight. 
  • Made by: Christopher Baker

3. Yahoo Mail Visualization

  • If you're curious about global email patterns at any given moment, check out this visualization of Yahoo's email processing. The interactive visualization shows the number of emails processed and trending subject line keywords (presently "Rachel" tops the latter, with 1341 instances in the last 20 seconds). There is no option to export or view historical data, but still, it's a fun exploratory tool. 
  • Made by: Yahoo, in collaboration with Periscopic.

4. OOM Creative ARUP Secret Life of Projects

  • This presentation depicts a project's digital footprint over time. One component visualizes the growth of an email network, and the location, billable hours, and sent/received associated with a  given node. 
  • Made by: OOM Creative