Yeast starters rock! I went for years without going to the 'trouble' of making them. Now, I won't brew without first making one. They jump-start the fermentation. I usually see activity in the primary fermenter within a few hours. Before I made starters, it would usually take 24 hrs! And, like the article states, they are really needed for high-gravity brews.
Here's a good thread on starters from a few days ago: Starters!