As a stand alone word most people understand the difference between pique, peek and peak. But when used in the context of: that _____ my interest, the incorrect word is often used. In fact, I've seen seasoned writers stumble over this.
It's easy to understand why. Many people use the word peak because their intended meaning is that caught my attention at a high point. Indeed, peak is a high point but it's not the correct choice in this context.
Pique is a French word. It is a transitive verb meaning to cause a feeling of interest, curiosity, or excitement in somebody. To stimulate, prick or provoke. To arouse a feeling as in interest or curiosity.
Peak is a mountain top, the highest point.
Peek is to look quickly.
The correct term is: that piques my interest.
Source: Encarta Dictionary: English (North American)