The new versions of both IE (Ver.8) and Firefox (Ver. 3.5) comes with a really nice feature called Private browsing built in without any need of any special addon or configuration.
But first let we talk about what really is meant by the term private browsing. As per Mozilla :
“Private Browsing,” allows you to browse the Internet without Firefox retaining any of data about which sites and pages you have visited.
HOW TO BROWSE PRIVATELY IN FIREFOX
To start a Private Browsing session:
1.Go to Tools menu in Firefox and click Start Private Browsing.
2. After this, Firefox will warn you that it will save your current windows and tabs for after you finish using Private Browsing. Click on Start Private Browsing to continue.

3. After you click start private browsing, a new window will open which will tell you what firefox private browsing will do and it wont any information in your private browsing session.
It also warns that even though firefox wont store any information during the session, still the Internet service provider or the employer (if you are on your office system) may track or store information related to your browsing session.
Firefox window’s title will change to (Private Browsing) during your entire session.

To end a Private Browsing session: go to Tools menu >>Stop Private Browsing entry.
HOW TO BROWSE PRIVATELY IN Internet Explorer (IE8)
1. Go to Safety options in IE8 Menu and click “InPrivate Browsing” .
2. A new IE window will open which will tell you about private browsing.

3. That’s it. You can now browse privately. The private indicator in your browser will remain till you dont exit the session.
To Close the private browsing session, just close the browser window.
- Browse web safely with WOT (Web of trust) Firefox/ IE /Chrome Addon
- PrivacyChoice Opt-out: Protect your privacy from ad networks
- All new great Features of Firefox 3.5
- 10 ultimate ways to make Firefox perform blazing fast
- Firefox 3.5 (Release Candidate 1) with private browsing Released
- Reset / Recover Firefox Master Password
- Navigate Firefox in 3D with Foxtab
- With Firefox 3.1beta 3, Mozilla bumps up Firefox 3.1 to 3.5
- How to Watch Hulu from outside US without Proxy or VPN
- Firefox 4 Beta 1 out: A sneak Preview