This one could get me in hot water. I know it has in the past. But I'm brave, so I'm going to forge ahead.
A quick preface: Strunk and White's Elements of Style is an essential book. It's the best, most concise style and usage book out there. It is, in a word, awesome.
But I disagree with them on one point. And here's an example of that point:
Adam went to the grocery store to pick up milk, juice, onions, potatoes, cream cheese, and oregano.
Yes, folks, I put a comma before the "and". That's the way I do it. That's the way I've done it for years.
We're taught in school... No, that's presumptuous; let me try again... Many of us are taught in school that we do not, under any circumstances, put a comma before the "and" when composing a list of things. Even Strunk and White tell us to leave it out.
Well, to quote Colonel Sherman T. Potter of the 4077th, "That is Grade A, one hundred percent, bull cookies!"
At least, that's my opinion.
Your mileage may vary.
Talk amongst yourselves...