Thyme is my favorite, followed by oregano and basil. I love mixing fresh thyme and oregano into a cheese blend of mozzarella and parmigiano reggiano to put on pizzas. I also love thyme and rosemary on lamb. Marjoram is another herb I like. I will occasionally put it in eggs - like a frittata.
As far as spices are concerned, cumin is one of my favorites. I can put that on almost anything. I love it in spice rubs too. One of my favorite things to put it in is guacamole. It gives it a great flavor. Spanish paprika, saffron, cinnamon, and nutmeg also rock.