Like its insanely popular Internet search engine, Google’s free Web e-mail uses uncomplicated antidesign to make information as easy as possible to find. By making the service available by invitation only, Google upped its desirability, and the 1-gigabyte storage capacity prompted competitors like Yahoo and Hotmail to increase their mailbox sizes to keep users from migrating.

BOTTOM LINE: According to research from Return Path, 54 percent of all Gmail users made the switch from Hotmail, while 33 percent had migrated from Yahoo, as of December 2004.