I didn't know my grandmothers very well, either (see Grandpas thread) but I had a great aunt who did all the things that Grandmas do. So:

Great Aunts are for:

Letting you try on all of her jewelry and shoes over and over again.

Baking brownies from scratch and mediating while you and your cousin fight over who gets to use the walnut chopper.

Staying up late curled up on the pull-out couch to watch Dallas.

Taking you school shopping and telling you to pick out one outfit you love, regardless of the cost.

Shoving money in your hand when your mother isn't looking.

She's been gone for 18 years now and I still think of her every day.