This one has some other GF mixes.  I use a mix of tapioca & corn starches, sorghum flour, and xanthan.

http://www.kidswithfoodallergies.org/page/recipe-page.aspx?recid=45

And I sometimes do a variation with almond. . . . add some almond flour in instead of some sorghum, use some amaretto, skip the cocoa. . . .

http://www.artofglutenfreebaking.com/2011/02/crazy-cake-and-welcoming-all-to-the-table-gluten-free/

1 1/2 C  Jeanne's Gluten-Free All-Purpose Flour Mix
1 1/2 C Bob's GF all purpose mix plus 1/2t of Xantham gum  (if using other all purpose mix, omit Xanthum gum if already in the mix)
1 C  granulated sugar
3 TBL unsweetened cocoa, sifted
1/2 tsp salt
1 tsp baking soda
1 tsp double-acting baking powder
6 TBL neutral-flavored oil, (I use rice bran oil) (I used olive oil)
1 TBL apple cider vinegar
1 tsp vanilla extract
1 C  cold water (or coffee or milk)

Preheat oven to 350 degrees.

To Make a Cake:
In your 8 inch square baking pan, stir together all dry ingredients.

Make three depressions ("wells") in the dry ingredients, 2 small and 1 large.

Pour your oil into the biggest well, and the vanilla and vinegar into the 2 smaller wells.

Pour 1 C cold water over all.  Mix well and smooth top.

To Make Cupcakes
Mix all in a large bowl, using the same order and process of the instructions above, and spoon into greased or lined cupcake tins.

Bake cake for 30-40 minutes at 350 degrees, or until tester comes out clean.  Bake cupcakes for 30 minutes, or until tester comes out clean.  For both, remove from oven and place on wire rack to cool completely.

Enjoy!