After all that lecturing about avoiding fat, I'm now going to tell you why it's nice to have different kinds of oil in your pantry.

Extra Virgin Olive Oil: it is the basis of French, Spanish, Middle Eastern, & Italian cooking, and most salad dressings.  

Dark Seseme Oil: you only need a tiny bottle of toasted seseme oil - use it like a flavoring - a couple of drops into your stir fry are all it needs.  too powerful to cook with!!!

Plain ole Canola or "vegetable" oil or margarine: Olive oil, peanut oil and seseme oil all impart flavors on the food.  when you don't want any flavor at all (ex. when baking a cake)  this is what to use.  margarine or butter work just fine, but tend to turn a brown color quicker (not the same thing as cooking your food quicker - they don't). 
also called: soybean oil, canola oil, saffflower oil, vegetable oil, etc.

Specialty Oils:

Shortening - necessary if you are making your own biscuits from scratch, or pie crusts.  not neccessary  if you are trying to cook light. Shortening is vegetable oil, HYDROGENATED, a process that makes it less healthy and more thick.  You really don't need this stuff much, unless you're going to bake from scratch.  As bad as shortening is, it was designed as the "healthy" replacement for  LARD, which is animal fat so full of chlorlesterol that it's a SOLID at room temperature..  ugh.

Deep Fry Oil
- if you deep fry, you want plain vegetable oil.  Don't deep fry in olive oil (it will smoke horribly).

Ghee - Indian clarified butter.  Butter is heated until the few remaining milk protiens separate (making cloudy white foam and then, if heated long enough, brown flecks).  The milk proteins are skimmed away, leaving just the fat.  Many french recipies and baking recipies call for clarified butter.

Tahini - tahini is ground up seseme seeds (seseme "butter").  On your shelf, it will separate, giving you delicious light seseme oil on top, and thick, chunky tahini on the bottom.  You get the same kind of separation with natural peanut butter (NOT Jiff!).  It is perfectly OK to drain the oil off for flavorings, and use the remaining chunky paste in your recipies.

Walnut Oil, Grapeseed Oil, other "
gourmet" oils: Experiment if you like.  No big deal.

Infused Oils:  geez, just make your own.  Too damn expensive.
Oils!!!!!!
Q.  What's all the fuss about Extra Virgin Olive Oil?   Don't I want Olive Oil with a little experience and an attitude?

Not really.  Extra Virgin Olive oil is from the very first pressing of the olives.  You're getting the best oil, bits of olive juice, and lots of chlorophyl (a good olive oil should be a rich dark green).  This is FLAVOR, you fool!!  Also, e.v. olive oil is incredibly good for you, go read the articles on it sometime. 
P.S.-  Kroger brand Extra Virgin is perfectly good, you
don't need to spend $20 on a bottle of olive oil.

Q.  What about Light Olive Oil?  "Light" means low fat, right?

Not in this case.  "Light Olive Oil" is just a lighter color, and a lot less flavor and chlorophyl.  There's nothing wrong with it, it's a perfectly serviceable vegetable oil, and you can use it for general cooking.  But remember, it used to be sold as the cheap "leftover oil" from the third pressing. your choice.

Q.  I pulled the black olive off the top of an enchirto at Taco Bell, to taste, and it sucked, big time.  Why do I want oil made out of this stuff?

Extra Virgin Olive Oil from any reputable company is made from a very different breed of olives than that limp little garnish that too many people are familiar with.  Trust me, there is better stuff out there.  Much better.