Replacing the Bathroom Sink
When we bought our house, the sink in the only bathroom was wall-hung and had about 8 different cracks through it. Not safe--the home inspector said it could fall on (and break) our feet at any time. We got a little bit of money from the previous owners to pay for new sink and plumber install, but being a moron, I (James) decided I could replace it myself.
The sink came off the wall and plumbing lines easily:

But I didn't know much about how the bracket was attached to the wall. In the picture above I've removed the medicine cabinet to see if behind it, I can see down into the wall. I couldn't see into the wall, but I did make a GRUESOME DISCOVERY.

There were literally hundreds of old used razor blades in the small space behind the cabinet. The cabinet had a small slot in its back wall, and some former resident of the house had slipped his used razors into it--apparently for a while. They poured out as I pulled the thing off the wall and just then I thought, "maybe I should have worn something sturdier than sandals for this." Luckily I didn't get cut.
In the end it took about 2 months to finish the sink. But it turned out beautifully:
