'barq' short for Barquentine, a character in Gormenghast.
I lived in a shared house some years back where we had a computer network linked to other nearby terrace houses. Many of the computers had names from Gormenghast (Sepulchrave, Steerpike, Swelter, Groan...) and I got used to logging in on 'barquentine'.
I use barq in a lot of places as I like to have a fairly consistent online identity. I shortened it to 'barq' because the symmetry of the lowercase 'b' and 'q' is nice. Annoyingly there is an American root beer of the same name, but I managed to register barq.org. The other problem is that because it is pronounced similarly to 'bark' people assume I must really really like dogs.