If one day, you should wake up and say "I want to create a blog with more columns than any other blog on the planet" (hey... you know who you might be), you might want to check out my blog to see how I've violated most principles of good web design in pursuit of that goal. (I think I posted this in the past... but that was when I only had 6 columns.) DocumentedLife.com
Why have I created a 9 column blog filled with 9 loosely correlated data streams flowing out of my brain, visible only on 1300 horizontal pixel wide monitors, filled with content that, really, could only be of interest to me and 10 friends, if I had 10 friends? (Ha. If you have to ask that question, you don't want to create a 9 column blog.)
For the record, it begins with an old WordPress 2.x installation which I do mean to replace soon with 2.6, followed by a books column (a php include of a complete list of every book I've read in my life, and also including a LibraryThing widget) followed by an rss feed from another site of mine, followed by a list of all movies I've seen, followed by a StumbleUpon rss feed, followed by a delicious feed, followed by a pictorial autobiography and genealogy (first web project I ever did, many years ago), followed by a WordPress link roll, followed by a few miscellaneous items, like login, rss and random quotes.
If you have to ask why, nothing I say is going to help.
If you enjoy the outlandishness of it... or anything else... I always enjoy hearing it.
If you know of other insanely columned blogs, I'd love to hear about them.
I think of it kind of like that image in the Matrix of data just streaming down like water running over the screen... except here it happens very very slowly. Each of the 9 data streams contains a different kind of meaning or story. Because they flow at different rates reading horizontally across the screen brings different components of those meaning types into juxtaposition.... oh who am I kidding? But I like it.