I used Gate Guru (clue's in the name) at Bucharest International this weekend and it came in handy for my transfer to my onward flight. There is a map of every useful internal airport on there and it links up to your email account to find your reservations for you. Can definitely recommend. Incidently I found the app on a blog from Truphone and they also recommend App in The Air which does the same thing, so maybe try them both.