I've heard Amiga's were used on the Sydney monorail, not sure in what capacity (its been discussed else where on here). I think they were also used in Sydney or Brisbane (cant remember which) to display train times, an Amiga user on here actually sent me the program that was used, still got to check it out.
A colleague of mine here in Adelaide said a hotel here used a C64 on the reception desk well into this 2000's. It ran a small guest database.
Too true on the monorail. Amiga 2000's, they control the station synchronisation and doors for the Sydney monorail. Now that it's being decommissioned there might be a few A2000s on the market.
The NSW rail timetable display system built and scrapped in the late 90's used A1200s.
HBA and Mutual Community (Health Insurance Companies) used A1200s in Video Generator boxes for Point of Sale information and adverts in their branches.
Hey Hey It's Saturday (Aussie TV program) used to use an Amiga for on the fly video titles and animation in the early 90's I think.
Lots of other stuff I think most people know: Early Babalon 5, Andy Warhol, Rolf Harris (Aust/UK Artist)