Modern airframe types clickable identification chart (Atlas / Sentinel etc). Think Top Trumps for the 21century
Links to FlightRadar24
Station Ops simulator (sorry, this runs more into new stand-alone apps, but I think a more-mundane non-expeditionary version of 'Operation X' would be so useful
An encyclopedia of valid aviation / military aviation related links. With votes up/down/evicts
A relaunch of the Air Cadet Wiki hints concept. Not just polishing shoes, but a sharing of 'the best personal admin knowledge'. Peer provided, votes up/down/out
Projects presentation areas. Youtube walk-throughs, similar concept to Instructables.
Career / Uni / College true-life stories page. Full persec redactions, all totally data-desensitised.
Proper International Air Cadet information and even programme comparison.
Exams practice generator. Multi-level. With/without answers revealed