Other than the update already delivered for computers running OS 10.6 and 10.7 Applerecommends users on 10.5 and earlier disable Java in their browser preferences.
The Wall Street Journal recommends several travel apps, including SeatGuru (free, Android, Apple) for finding the best seats to reserve on a flight, and Seat Alerts (free, Android, Apple) which can notify you when desirable seats become available.