Incoherent cake typology

I know (as in, I am confident of baking and tend to get good results with) about three and a half cakes:

1. the Christmas cake where you glue together fruit with a batter made from equal parts butter, brown sugar, eggs and spiced plain flour (start by mixing butter and sugar; then add beaten eggs; then add flour) and totalling about the same weight as the fruit, then bake slowly for some hours


2. Chocolate brownies, where you melt together equal weights 'x' of dark chocolate and butter, beat together about 1.5x sugar and 0.75x egg, mix the two liquids, then add flour-or-ground-almond and raisins-or-walnuts-or-contrasting-chocolate-chips until the texture is right, and bake about gas mark four for about half an hour


3. Sponge cake / chocolate cake (this is the 1.5), where you mix (vigorously with an electric whisk) in a bowl equal weights of self-raising flour, soft butter, eggs and caster sugar, replacing a quarter of the flour with cocoa powder if you want a pale chocolate cake and half of the flour with cocoa powder if you want a dark chocolate cake, and bake roughly like the brownies

I expect there are quite a lot of other kinds of cake which are as different from these as a Christmas cake is from chocolate brownies ... a bit of Googling suggests some Swedish ones where the liquid is saffron-infused milk, and I remember making a lemon drizzle cake which involved more than adding lemons at the caster-sugar stage and making a lemony drizzling syrup.

So: people with a much wider knowledge of the space of tasty cakes - can you suggest a point as far as possible from the ones I've explored already, so I can go there and widen my knowledge? I'd like things which are definitely cake, rather than bread or biscuits.