There's nothing you can't do with beer, mix and match. 30 years ago they said I couldn't mix ale and lager, my response was why not?!
Grapefruit and beer I wouldn't recommend, it's too bitter.
Raspberries, cherries, apple, honey, I've tried them all and they were fabulous.
Adding more sugar to get a higher alcohol content to get 'barley wine', doesn't taste as good but it'll get you in trouble faster.
What are you beer experiments, how did they turn out?