I got the house powerwashed. It took me 6 months to decide that this wasn't some ridiculous extravagance and another 6 months to find people to do it, get an estimate, reserve a time, and have it done. I love it. My house looks brand spanking new. All the green slime is off the siding. All the black goop is off the front porch. The stairs are no longer slippery with mold (that was actually the final impetus, when a friend slipped and fell badly on my slick steps). And the bricks, who knew they were this color? Everyone who comes to the house is in awe. The last big house expenditure was for a sewer pipe that wasn't even broken (long very annoying story), so to be actually able to see and appreciate what I paid for is delightful.