Since you posted this 20080708 I'll assume you're using Firefox 3.0. Tools>Options>Advanced>Network>Clear Now

Thanks!

Simple process however there are several different ways to do it and several details should be noted. You can also clear the cache each time you exit firefox. All the details can be found at a link I found: http://www.groovypost.com/howto/firefox/clear-firefox-browsing-history-and-private-data/

If you have Firefox 3.0.3 I can help you. To check what version you have goto "Help" and then to the bottom where you will see "About Mozilla Firefox". There it will tell you the exact version of Firefox you have. I'm going to assume you have 3.0.3. Goto "Tools" then goto "Options". This will bring up a Tabbed window. Then click on the "Privacy" tab and at the bottom it will have a box called "Private Data". In there you can select "Settings", "Always Clear My Private Data When I Close Firefox", and "Always Ask Me Before Clearing Private Data" These last two you will have to click the check box and apply your settings in order for it to work. You will also notice another button that says "Clear Now". This is the one if you want to click if you want to do it manually, and "Now". Once you click this, a dialogue box will open up that gives you a vast range of options. You can select "Cache", "History", "Passwords", etc. Once you have finished making your selections, click the "Clear Private Data Now" button and your good to go! I really hope this helps.

Hey man, I don't know if you'll get this, 'cause it was a while ago that you asked your question, but there's a new version of firefox that is currently in the beta stage that will be released very soon, and it has a feature in the "Tools" menu that you can activate called "Private Browsing Session". The following is a detailed excerpt regarding Private Browsing, which I found at http://www.webmonkey.com/blog/Firefox_to_Embrace_Porn_With_New__Private_Browsing__Mode. Private browsing, or “porn mode” as it’s often referred to, since that’s one of the more obvious uses, restricts the information that your browser gathers as you visit websites. Cookies are rejected, URLs are kept out of the browser history, forms are not auto-filled and pages are not cached. The result is a browser session that — from the browser’s point of view — never happened. While the cynical might claim that the major use for private browsing is porn, there are some other times it comes in handy — on public computers, for instance, where you don’t want the browser tracking your banking or e-mail logins. If you can't wait until the release comes out, you can goto http://www.mozilla.com/en-US/firefox/all-beta.html and download it, coinciding with your OS, of course. However, if you do decide to download the beta version, some of your add ons (actually most) won't work, for example, Fire Gestures, Fasterfox, Yet Another Smooth Scrolling, etc. Or you could just Wait until Ver 3.1 comes out; shouldn't be too much longer.