TODO (in no particular order)

A lot... :)
Make all config vars as ARGS and vice versa. ARGS have higher priority. Chain: default -> config -> ARGS.
~~Parallelize queries using threads to improve performance; Does not work using SQLite because of exclusive access to the database~~ DONE
~~SQL server backend; MariaDB/MySQL?~~ DONE
Bring back SQLite support
Switch to ORM (peewee?) to support PostgreSQL, MySQL and SQLite.
Gtk+ frontend connecting to the database or loading a local copy of a SQLite file. wxGlade?
~~A cron mode to not let uplink run in an endless loop to be scheduled and executed by cron.~~ DONE
A daemon mode to be a real UNIX daemon. For now, it's just sleep() based.
Always keep platform independence in mind but not if uplink looses nice features on Linux.