I've had the Neighbors From Hell before also, so I can totally empathize with all of you who have posted nightmarish stories so far!
Right now, I live in a condo, so things are much better. But there are still annoying neighbors with whom I have to contend. One guy, 30-something and jobless whose parents pay his monthly house payments and living expenses

, bothers me and my next-door-neighbor at least twice a day. He usually comes up with some stupid excuse like needing to borrow saran wrap in order to get in the door.
Then, just when we've handed him the requested item and shooed him to the door, thinking that we've got him out of the way for a while, the leech returns to bring us a "Thank you" bottle of Zima. It's quite obvious that the drink is just another excuse to come by and invite himself in for a while, and since it's become a daily occurence both I and my NDN have gotten extremely tired of Annoying Guy knocking on our doors all the time.
It's gotten to the point where neither I nor my NDN will answer our doors if we see him through the peephole. My NDN even got caller ID so that she could screen her calls, because he would knock, not get an answer at the door, and then go back to his place and call to see if she was home!
Whenever we come back from work or running errands, we pass by his condo on the way to ours as quickly and quietly as possible so that he won't know that we're home. There's just something about him that gives us the creeps. I'm sure some of you can relate to that, right?
Anyway, I know that's a minor story compared to some of y'all's but I felt like sharing.