I could go on for hours about ideas...but I'll save you some pain. I've found a good link which has more than 9 pages of visual ideas of sloping gardens.
You might find this more inspirationally as opposed to words. I have to say, some fab ideas....and they don't have to cost the earth. Just needs a creative mind.
I'd like to cut in some little terraces or just a spades worth of ledge and then anything trailing say petunia's falling down the slope