Geoff, as Brian mentioned above, there are ways of tracking commercial aircraft. The one I sometimes use is this one:
**LINK**
if you "tune in" over Newfoundland in the evening, it looks like an invasion happening – all the overnight flights to Europe. And, those high-flying flights over my house are freighters to/from China. (at least, that's what's reported)
(It is interesting how it gets its' data – read about it on the site)
You can also build your own tracker – go to **LINK**
and search for "ADS-B".
Fun stuff!