The LEGO Stores feature the Pick A Brick Wall, where you can buy a small or large cup of LEGO bricks. The selection changes every now and then.
Where can I find the current bricks that are available at the LEGO Store?
The bricks in the Pick A Brick Wall are subject to change. As soon as the supply of one type of brick is exhausted in a store, they replace it with another type of brick. There is no particular rotation or order, it is just whatever happens to be in the delivery that the store gets from Lego.
Selection varies by store and the elements are always changing
The brickbuildr.com website has a section dedicated to an effort to inventory each Pick A Brick Wall through submissions from the community (not the Lego store itself), but it is often a little out of date.
I wrote a website where users can update the contents of the Pick A Brick wall for various Lego stores. The site is http://www.wallofbricks.com/
I used my iPhone to inventory the wall at the Lego store in Orlando, FL. If you inventory your local store please send me some feedback on how the process works. I tried to make the GUI easy to use from a cell phone so that you can inventory a wall quickly.