Firefox is alright. I keep around a script called `chrome-new` for those rare case I still need Chrome.

  #!/bin/sh
  if [ -z $CHROME ]; then
      test -e "$(which chromium)" && CHROME="chromium"
      test -e "$(which google-chrome)" && CHROME="google-chrome"
      test -e "$(which google-chrome-stable)" && CHROME="google-chrome-stable"
      test -e "$(which google-chrome-dev)" && CHROME="google-chrome-dev"
  fi
  TMPDIR=$(mktemp -d /dev/shm/chrome-XXXXX)
  $CHROME --user-data-dir=$TMPDIR --no-first-run --no-default-browser-check "$@"
  rm -rf $TMPDIR