Script Summary: Add an available balance line for pending charges/credits
It always bothered me that Zion's Activity ledger for your accounts didn't show a balance for pending debits and credits. In particular, this makes it quite easy to think that you have a positive balance when in fact you're about to get slapped with an insufficient funds fee.
This script is very straight forward. Without reorganizing the existing layout of the page, it creates an additional balance column. This column is identical to the existing balance column for all cleared transactions but also incorporates any pending charges/credits. Additionally, for clarity it highlights pending rows and adds a line separating different days to make it easier to see what your balance was at the end of each day (however, see disclaimer below). The styles used are congregated at the top of the script so it should be fairly straightforward to modify them or set them to empty if you like the new balance column but not the style changes.
DISCLAIMER: I can not be held responsible for anything bad that happens due to you using this script. I promise (and you can obviously check the source) that there is nothing malicious in this code. It never loads any other urls. Even the css used is self-contained. However, it does attempt to show you information about balances which cannot be consider official. Your bank won't care if you try to tell them you made a mistake because of some script you installed that confused you.
The available balance shown is still just a best guess based on the way Zion's displays transactions. Internally they maintain a balance which is calculated differently than what is displayed in your online Activity page. In particular, transactions are not necessarily deducted from your balance in the order shown and transactions occurring after 4pm are actually pinned to the next "bank day" even though that is not always clear.
For that reason, the bank calculated balance is still shown (see provided images).