Here.
I am also doing (nearly) everything still with my Mac OS 9 machines. Still a lot of layout with XPress, some stuff with Freehand, PS, etc. Also I am driving several digital printing machines with my 9 computers. Some Konica-Minolta Copiers, some LFP (Plotters) and so on.
I think ArchiCAD (is 6.5 the latest one?) can also still produce professional files, similar to Photoshop 7 that can also still be used without problems if you do not need some very special new functionality of the most recent Photoshop. I´d suspect some rendering stuff and such.
Really annoying is that the internet situation with the latest SSL encryption. Several websites even do not communicate anymore with our webbrowsers and mailclients, so you need an external proxy, like Knezzen pointed out, ... One of the few things I really need an external computer for in the meantime was when my bank switched the online banking to some "smartphone interface" with lots of JS and CSS, some years (2 or 3) ago. :-(
But in general I still do everything with my Mac OS 9 machine. My advantage is for sure that I never was interrested in any "social" media. ;)
