Please submit all links of stats, facts, proofs, tools and/ or anything that we can use to build powerful cases as to our recommendations in the field.

Measuring Usability
http://www.measuringusability.com/
This site allows you to use probability/actual based calculators to develop stats for usability findings and generate reports.

Mail Chimp

http://www.mailchimp.com/resources/email_marketing_benchmarks.phtml
Average open, click, bounce and abuse complaint rates by industry

W3C Schools

http://www.w3schools.com/browsers/browsers_stats.asp
The best stats to use when making your case are, of course, from the
website in question because all sites will have a different usage
profile, but if you don't have these, or need to make a stronger case
for, say, dropping all your IE5.5 CSS hacks, the w3schools stats can
be useful

Characterizing Browsing Strategies

http://www.igd.fhg.de/archive/1995_www95/papers/80/userpatterns/UserPatterns.Paper4.formatted.html
Some browsing strategy research. It's from 1995 (anyone have anything
along the same lines that's more recent?) but can be useful if you
need to make the "don't break Back button functionality" argument

A List Apart

http://www.alistapart.com/articles/zebrastripingmoredataforthecase
Recent alistapart article on usefulness of zebra striping in tables

Campaign Monitor

http://www.campaignmonitor.com/css/
If you need to, e.g., convince someone that it's a bad idea to use the
style element in your head or body elements when developing an email
newsletter or marketing campaign

Email Stat Center

http://www.emailstatcenter.com/Creative.html
A plethora of statistics from various sources on preview pane in
Outlook usage, image blocking frequency, etc. Some of the research is
of questionable value, and the frame-based navigation is annoying.

Google Trends
http://www.google.com/trends
With Google Trends, you can compare the world'sinterest in your favorite topics. Enter up to five topics and see howoften they've been searched on Google over time. Google Trends alsoshows how frequently your topics have appeared in Google News stories,and in which geographic regions people have searched for them most.

Internet World Stats
http://www.internetworldstats.com/stats.htm

Email and Webmail Statistics
http://www.email-marketing-reports.com/metrics/email-statistics.htm