Taken from the Herbology T-Y article:
VANILLA BEANS: Magickal uses include love, lust, passion, and restoring lost energy. Carried to increase energy & strengthen mental abilities.
Personally, I consider vanilla as cold in opposition to cocoa which I get a warm feel from. Interpret that as you will. Vanilla is one of my favorite scents and flavors, and I'm currently experimenting with it in a variety of potions.