The JAS backend should have a help section included. Probably the easiest is to just reference the online documentation "Backend" on the website. One idea is to have an ? icon somewhere which shows the related documentation pages. This can than automatically download and show the content on the website.
Currently only the initial installation is foreseen, however upgrades should be easy to install as well. This could be handled in a similar fashion as plugins, i.e. download the latest version and upgrade JAS using the backend.
Currently the MIME database (include/mime.xml) is a static list provided as part of JAS. It would be handy if this list could easily be updated via the backend.
The question that comes to mind however is whether upgrade should overwrite a customized version. It seems rather annoying if you spend time to add your own MIME types that are subsequently forgotten when JAS is upgraded. Maybe adding a flag "custom" to the XML file to indicate it shouldn't be touched by upgrades.
The JAS backend should have a filter section to more effectively drill down in the data. the filters should be automatically generated based on the module (similar to the CMS). Text fields should have a inline dropdown with available values (like the search box).
Additionally it should remember the last set filters if the user comes back to the page later. This will require a "Reset" button to set all values to their defaults.
One nice feature would be to have statistics page that allows you to dynamically generate any type of statistics on the various modules.
Some examples:
Total rows per module (already in database section)
Adds/Updates per day
Top used categories
It should be flexible to allow any type of statistics to be pulled using the aggregation fields. It's probably handy to be able to store presets so they can be easily rerun later (prolly wise to store them in the "JAS" project so the...
The JAS backend should support recursive delete options.
Note that this probably also requires recurseCategories / recurseContent to be submitted in the CMS. This is probably best done by setting use=form.