This is the best cake recipe I've ever found, on the grounds that it is: criminally easy to make; very tasty; easily hacked to produce variations; and easy to carry once it's made (hey, this matters if you're taking cakes to parties, on picnics, etc!)
That's it. Really.
'Brown sugar' is pretty vague. I usually use golden granulated sugar, but dark brown muscovado makes a more sticky and treacly cake, and white granulated sugar works fine. To be honest I think it'd work with anything. Have a go.
This cake always seems to be a bit sticky in the middle no matter how long you cook it for. I think this is a function of fruit-cakes rather than a problem with this recipe... The knife-test (stick a knife in, if it comes out non-sticky the cake's probably cooked) is still useful but don't expect the knife to come out completely clean. For one thing, you've got all that cooked sticky dried fruit in there. If the raisins sticking out on the top are starting to burn, it's probably done. There's nothing in there that'll do harm for not being cooked.
With the ingredients above, it makes a fairly standard fruit-cake. Add spices (cinnamon, ground cloves, mixed spice, whatever you fancy) to make it a bit spicier. Add weirder dried fruits (papaya, pineapple, coconut, nuts, whatever) if that's your kink. Glacé ginger works well, but using ginger beer as the liquid may be a step too far (it makes the cake rather too full of air-bubbles). Use coconut milk (and add dessicated coconut, perhaps?) to make it, well, coconutty. And of course if you use soya milk, coconut milk or water for the liquid then it'll be suitable for vegans, unless people have started putting weird stuff in all-bran or dried fruit while I wasn't looking.
My aunt Bev claims to have invented this cake, but variations on it can be found on the back of all-bran packets occasionally. It was my standard take-to-parties cake when I was a student, and it was known as 'fruitcaaaaaaaaaake!' as lurking fnorders might already know (I was 'fruitcake' on irc at the time).