From what i can tell, there is no way to check pending charges on the American Express website...but you CAN do it on the American Express iPhone app...
Am i missing something or is this just a weird/slightly annoying thing...?
If you log into your account (charge accounts, not sure credit cards are set up yet). Then click on the account details or something it is right above or below the account name and then up in the corner on the next page (on left above account) you can see view pending transactions.
You can see pending charges. Log in to your Amex account, hover your mouse cursor over the "Statement & Activity" tab, click "Recent Activity". Once you're on that page, you'll see "View Pending Transaction", click on it and you're there
For some reason that didnt click because it looks like a title or heading instead of a button.