Google Chrome
Google Chrome can be forced to run in “Incognito” – private browsing mode when you launch it, by adding a simple command line switch. In Windows, right click on the Chrome shortcut and select properties. In the target area, just add –incognito to the end of the string. For profiles, use:
C:\Users\<username>\AppData\Local\Google\Chrome\Application\chrome.exe -incognito –user-data-dir=”..\User Data\<username>”
Mozilla Firefox
Firefox can be made to run in default private browsing mode, by adding the command line switch –private to the end of the target.
Internet Explorer
As with Firefox, add the command line switch -private to launch Internet Explorer in InPrivate mode.
Opera
Since Opera has per-tab private browsing (unlike the others), adding the -newprivatetab switch will load both a blank, private tab and whatever your startup preference is set to (last tabs, speed dial, etc.) in standard browsing mode.