Google Code Blog: Introducing the Google Font API & Google Font Directory.
The Google Font API provides a simple, cross-browser method for using any font in the Google Font Directory on your web page. The fonts have all the advantages of normal text: in addition to being richer visually, text styled in web fonts is still searchable, scales crisply when zoomed, and is accessible to users using screen readers.
GTmetrix uses Google Page Speed and Yahoo! YSlow to grade your site’s performance and provides actionable recommendations to fix these issues.
24 ways: Rock Solid HTML Emails explains how to code and style Emails to make them look good on all most email clients..
The email client market share as of January 2010. These numbers are not exclusive – some people used more than one email client during the month, and so that will register a vote for each client used.
via Email client popularity – Email Stats & Reports – Email Clients – Campaign Monitor.
But beware: GMail and Outlook2007 are underrated in this statistic: The email client a person is using can only be detected if images are displayed. This can give an inflated weighting to email clients that display images by default, such as Outlook 2000 and the iPhone. It will also provide a lesser weighting to those that block images by default such as Gmail and Outlook 2007.
Hotware: Dirk Paessler's Software Blog 