NaNoWriMo has started its registration period this year and got such a number of queries that I can call it a DDoS. Registration is now off. The server couldn't handle the load.
It's interesting when it happens to someone else. With a dynamic site 1000 people at the same time is too much, so DDoS for a small (or medium-size) site is not that hard. Sometimes just because it's too popular.