The empower and cigarette-lighter plugs mentioned in earlier posts cover every airline seat power supply you're likely to encounter now or in the future, so if you get an adapter that handles both of those (all the major ones do) you're all set.

The other end varies with the computer you have. There are dozens of computer plugs. You have to tell the adapter vendor what you need. All their lists include Macs, so don't worry about your "minority" status (which I share) in this context.