When I first started blogging, if I wanted to make a point, I would use an exclamation mark! I guess I had a lot of points to make because when I look back at my earlier posts there are a lot of exclamation marks!!!
It was pointed out to me that this was a common mistake and the more you use them the less effective they become. A period makes the point, without using an exclamation mark.
See Susan Johnston's post today on The Urban Muse. Someone commented that exclamation points "should be shot on sight".