...Don't play Minecraft with a mouse that has a "back" button programmed to it...or at least don't play in the browser.
I have a Logitech Mx510 with the back button sticking out from the side of it. On more then one occasion i went to grab the mouse and bumped it which erased hours of progress. I had my own little underground work area which produced a lot of nearby diamonds. I had also built a diamond pick axe. All thats gone now. Technically it should still be in the last place i found it but it took great strides to make it happen the first time and even then i won't know exactly where to start digging again.
 
So, remember to save often, beware of accidentally hitting the "back" button, or play the DLed version of the game to avoid this problem.

Anyway, all that said, i'm having a pretty good time with it and am curious to see how it grows. though i'm sure there's a wish list thread here somewhere i'll just add, i think it would be keen if they had male and female animals that would breed more animals. I could then keep them fenced in and slaughter all the pigs i need.

They would have to model low polygon penises and vaginas on the animals. 
 
Disturbing thoughts.

"So, remember to save often. "

I did this once. Only once, thank god. Lowercase.

And i thought i had it bad when i got killed after finding a large sum of diamonds and not being able to find where my fort was. I literally searched for 2 hours looking for it. 

Who doesn't always open things like this in new tabs?
 
That sucks and all... but dude