Cool story (thanks, Jim!) in the Strib about a woman who is walking every street in Minneapolis. This has less cultural cachet than walking every street in Manhattan. Minneapolis has 370 extra miles of street, however.
Good luck to her! I once ran every street in the western suburbs of Wellington. It didn't take me long, and I learned that I really did prefer the trails. And that was in a city where the absence of a grid system and many undulations made the endeavor more interesting (if harder to plan). Occasionally I amble through Longfellow on my runs in Minneapolis. If you've seen one of the avenues, you've pretty much seen what the rest of them look like ...