Most web marketing experts will tell you that the secret to a successful blog is to narrow your focus. Find a niche that nobody else is writing about, and write about it.
So how's this for focus: A blog that's devoted to the Rideau Canal Pedestrian Bridge. Dozens of photos, posted almost every day, with archives going back to July 2005. It's written by Charles Akben-Marchand, a University of Ottawa student who walks by the bridge on a regular basis.
Not sure how much longer the blog will be updated though -- the bridge opened last week.
Related: Ottawa Blogs Guide