"Originally, it was a challenge to myself to create a new game idea or gameplay mechanic once per day for 300 days. I failed this challenge and stopped updating around entry #050. However, it is still my intention to fill up this notebook of ideas to the full three hundred one day, though at a more leisurely pace. "
Basically, this guy thought of 300 mechanics he had never seen before, and put them on a website; However, he did mean these to be used in Video games, not board games. Most of them are for turn based games, which can easily be used for board games, and those that aren't can still give inspiration.