Hands down the best cookies I've ever tasted. I make then all the time and am always asked for the recipe! Sometimes, instead of raisins, I put in chocolate chips, and (my favorite) chocolate covered raisins.
Sift (sifting is important!) flour, baking soda, baking powder, salt, cinnamon, nutmeg (its not in the recipe, but I add about 1/8-1/4 tsp of ground cloves, too) into a mixing bowl.
Beat butter, brown sugar, sugar, eggs, and vanilla with a hand mixer at medium speed.
Sift (yes, again!) flour mixture into butter mixture and mix well.
Fold in raisins (or chocolate chips or chocolate covered raisins) and oats.
Spoon 1.5 inch balls onto non-stick cookie sheet.
Bake at 350°F for 6-9 minutes, rotating half way through baking. (Should be lightly firm in the center when done) Be careful -- oatmeal raisin cookies don't look done when they are, so they are very easy to over cook (unless you want then to be crispy) :).