Yes I have! Saw one boarding my LHR-BHD bmi flight some years ago and spoke to them, and was spoken to last year by a lurker who spotted mine in SIN or BKK ( I was in transit and cant remember at the moment!). A fellow FTer called over with me in the SQ lounge in SIN in November on seeing our tags.
They are more common in the states than Europe though.
I have a few on my rollaboard and carry on luggage, and that of Mrs Antichef.
SanDiego1K seems to be the only source of new ones at the moment.