This is what I was trying to describe in the JJNA post.
You get some screen at OSH (the holes are about 1/2") and cut it into 4" strips (about 9" long in this case). Then bend it to fit over the downspout holes. My gutters are "Ogi" (sp?) so it took a little extra bending on the corners that are hidden in this photo. The fit isn't too critical, though. You just need something that will stay there and not be blown away by the wind. Don't just lay the screen down flat over the downspout hole. If you do, the leaves will end up laying flat on top of the screen and prevent the water from going down - not the desired result. If you give the screen a little height, then the leaves sit next to the screen and let the water pass through.
It really works and don't have to clear the crud out until you see small trees growing in the gutters ;->
I must give credit to my co-worker: Joe Wang. He came up with the idea. He lives in Saratoga where the rain can be much more intense than the usual San Jose sprinkles and he really didn't like clearing the gutters every month.
Oh, I almost forgot to mention Joe's other brilliant gutter discovery: TONGS. Get yourself some cheap metal tongs (get a new pair for the kitchen - you probably wont want to use the gutter tongs on food) to pull the crud out of the gutters. Joe reports that his kids all fight for the chance to clean the gutters with the tongs.
Bob