I did my GCSE electronics last year (A* as well...) and to be honest, its alot less difficult that you expect.
Bassicaly, to be eligible for full marks (which I got!! ok, i'll stop bragging now) you only need two process blocks. So I used a 555 timer, and a 4017. The outputs of the 4017 had LEDs on them, to make a simple dice. A push button connected to the 'stop' pin stopped the counter randomly and lit a random LED.
I made a couple of additions, to try and impress the examiner, but that was pretty much it.
Not meaning to be rude, but intead of just asking us to randomly suggest stuff, you really need to talk to your teacher to get ideas for areas to look into. For example we were told to look at alarms, counters and sensors. And told not to look at RF/IR/Audio. Do this first, then come back. We can help you adjust ideas/diags to suit your purpose, but you will have to be able to explain what you did in your coursework folder.
Also, look in your textbook, it should have loads of diags that you can use. (if you don't have one, your teacher should have books that you can look in).
Tim