I have more connecting flights than most. Some of the things I spend my transfer time doing

relaxing in airline lounge
drinking
eating (depending on what is/isn't on offer during the flights, choice of sleeping, etc)
meeting friends (or FTer strangers)
drinking
reading
walking laps of the terminal
checking out artwork/exhibits/etc on display in the terminal
wander around the neighbourhood (not practical or safe at some airports)
taking a shower (makes me feel better and smell better)
drinking
catching up on email/phone messages
checking out FT
working
head into city/surrounds for longer transits
sleeping
people watching
thinking time
etc

I very rarely manage to get bored - there is always something to do.