Make Bittman's No Knead Bread from the New York Times. It's a delicious, crusty bread with large holes:
Original NY Times article about No Knead Bread with recipe
Article about fine tuning No Knead Bread
YouTube Video showing how No Knead Bread is made
Here are some Chowhound links
No Knead Bread - 1 year later
Bittman's No Knead bread is out of the oven, anyone else?
Here's some info about making bread with large irregular holes:
WINGBOY'S LOVELY HOLE-Y BREAD
It didn't make sense until someone explained what was going on. The long rise makes a lot of gas bubbles and leavens the mixture. The recipe says to fold it over itself a couple of times before the second rise - this is to evenly disperse the gas bubbles. First few times I did this it really just was a fold over, and I got huge bubbles (which I wasn't happy with). So now I do a fold-over-flatten-out-fold-over-etc thing which makes it more even.
So no it's not over-mixing (which happens at the beginning before there is gas) but it could be over-folding before the second rise.