iPaB. Now on the summary page for each store, you can download the summary to a CSV file.
What next, you may ask? Well, print it off, take it to your local LEGO Store and verify what it says in the spreadsheet still holds true. If it doesn't, there should be room (under each part description) to make notations. Then at your leisure, go to the BrickBuildr web-site & update your store's inventory! :)
Let me know if there's any problems with the download.