This is called "New Incognito Window" in chrome/chromium, or a separate profile in Firefox. What would be really nice, though, is the ability to have a bookmark open in an incognito window. The separate profile in Firefox is better because it'll keep cookies between sessions so you don't need to keep logging into facebook.

I also use this:

  #!/bin/sh
  
  test -n "$CHROMIUM_COMMAND" || CHROMIUM_COMMAND=`which chromium-browser`
  test -n "$CLEAN_CHROMIUM_TMPDIR" || CLEAN_CHROMIUM_TMPDIR="/tmp"
  USER_DATA_DIR=`mktemp -d "$CLEAN_CHROMIUM_TMPDIR/clean-chromium.XXXXXXXX"`
  
  case "$1" in
      cleanup)
          (cd "$CLEAN_CHROMIUM_TMPDIR" && find . -name "clean-chromium.*" -print0 2>/dev/null | xargs -0 -r rm -rv    )
          ;;
      *)
          chmod 700 "$USER_DATA_DIR"
          echo "CLEAN_CHROMIUM_TMPDIR = $CLEAN_CHROMIUM_TMPDIR"
          echo "USER_DATA_DIR = $USER_DATA_DIR"
          echo "CHROMIUM_COMMAND = $CHROMIUM_COMMAND"
          echo "Running '$CHROMIUM_COMMAND' --user-data-dir='$USER_DATA_DIR' $@"
          "$CHROMIUM_COMMAND" --user-data-dir="$USER_DATA_DIR" $@
          find "$USER_DATA_DIR" -type d -print0 | xargs -0 -r chmod 700
          find "$USER_DATA_DIR" -type f -print0 | xargs -0 -r chmod 600
          ;;
  esac

"Tools" -> "Start Private Browsing" in Firefox

control-shift-P works as well (probably command on a mac but I don't have one)

But really chromium/chrome has the best implementation as it creates a new window and doesn't destroy your session.

In Firefox, the session isn't destroyed, instead it is saved until you choose "Tools" -> "Stop Private Browsing". But, the chromium implementation might be more convenient.

Can't someone develop an extension that prevents cookies from being accessed inside iframes (white/blacklist)? Wouldn't that stop the whole problem?

Or simply block the facebook iframe urls?

Isn’t this what enabling "block all third-party cookies without exception" in Chrome or disabling "accept third party cookies" in Firefox does?

I almost exclusively use FB on my iPhone (with Location turned off). It's the only way I can parse the stream while staying sane.

There's an app for that.

Are you guys kidding me? The guy above me even said he only browses facebook on his iphone. Using a dedicated app solves the privacy problem!