Speaking in tongues: great stuff. Great because it makes nearly all of us (including those who have the gift) feel pretty weird or uncomfortable.
Non-Christians try not to think about it unless they need something to ridicule, and Christians try not to think about it because it's a bit out of our comfort zone and we'd really rather prefer God to be more sensible.
So whatever you think, have a little look at this video (particularly from 2:40 onwards). A (Jewish) neurologist, investigating the relationship between glossolalia and activity in the frontal lobe of our brains. Interesting stuff.