...and I'm not saying which one. (OK, I'll give you a hint; he's the one on the right -- but I'm not saying if it's the one on the right when I'm in the house facing out, or outside facing the house.)
Whenever I shovel snow from the sidewalks I make sure I shovel at least a noticeable distance over the property line on either side. Maybe a shovel width, maybe a little less...but I make sure that it's really clear that I wasn't being persnickety about my snow vs. their snow. It's not really a big deal, but I'd feel like a dick if I didn't do it.
One neighbor is the same way. If he's out there before I am, I always find that he's shoveled a little further than he technically needed to.
Tonight, I went outside to shovel up the final couple of inches of snow and the douchey neighbor had done his walk before I got out there. First of all, I'd swear he laid down a chalkline to make sure he had a clear delineation between what he considered his snow and what he considered my fucking problem. The only thing is...he decided to draw the line at the edge of his steps...not including the stonework banister.
If I were more of a dick, I'd have left a 4" berm of his snow.