I've historically used 'echelon' everywhere since 2001. It's my Gmail address, my Github account, and while I don't tweet much, it's also my Twitter handle.
I was so disappointed when 'echelon' was already allocated on Reddit and HN. It took me years to sign up for either site because I was put off by having to use an alternate username. Ultimately I registered here as 'possibilistic'.
Just under a year ago I randomly tried to register as echelon again; I suppose pg deallocated all of the unused accounts of a certain age--I got my originally desired username. My problem now is that all of my posts are under 'possibilistic'. As much as I'd like to be 'echelon', I like my comment history too. :-/
I wonder if I could bother someone at HN to rename 'possibilistic' to 'echelon' and just delete this account entirely? It's probably not worth their effort, but it would be really nice.