There's a good wine you can make with blackberrys and crab apples. I'll fish it out. Also elderberry and blackberry wine is a good combination. You might find pressing juice out of crab apples is quite difficult without a fruit press/juicer though. Most recipes I've seen recommend using windfalls, maybe so that they're easier to press.

Just had a fish about on the internet and found this site: http://homemadewine.net/recipes/recipes.html

looks like some really great recipes, I particularly like the sound of the plum melomel! Mmmmm. No plum trees round us so maybe someone else could try it out if they have a glut they can't think of how best to use?