The same summary of updateable addons that shows on the ACP index (if enabled) also shows on top of the add-ons page (by default on, can be disabled in options)
The 1.0.3 release had a bug where uploading through FTP + finishing the addon update would fail since it tried to access an unknown option (since it wasn't yet installed).
This release handles that error, would the option not yet exist.
When clicking the "Get your API key here"-link in the addon options, it passes along your forum's boardUrl so you don't have to worry about getting the value right
Some forum owners have downloaded and installed without configuring the API key, this fix prevents their forums from calling the API with invalid requests
Here is a list of the top 90 most used XF addons by our users. This list should give you an idea of which addons are probably worth installing on your forum.