Being a big fan of coffee, I’m always looking for variations on the usual beans, hot water, sugar, cream recipe. I’ve found that flavor extracts (like you’d use in cooking) are yummy in coffee. I use vanilla extract, almond extract, hazelnut extract and mint extract. A drop or two per cup is enough, so the little bottle lasts a long time, and they add virtually no calories (as opposed to the flavor syrups you can buy from Starbucks and such) if you’re worried about that sort of thing.
For fruit flavors, I’ve found a tasty option is using drink packets — the kind that you pour into a bottle of water. Obviously not all of these are suited to coffee. I suspect lemonade coffee would be gross, though I haven’t tried it… But raspberry and strawberry are excellent flavors for coffee. I recommend NOT using a whole packet, unless you’re making a full pot of coffee. For me, about a third of a packet in 12-14 oz. of coffee works best.
Another favorite coffee hack is coffee cubes. You pour coffee into an ice cube tray and freeze. Very easy, and no watering-down of iced coffee drinks. I make mine out of decaf to avoid over-caffeinating. :) Also a good idea is to have a dedicated tray just for coffee cubes — they leave a film of coffee oils on the tray. I read about this on the Internet, but it was a while ago and I’ve forgotten where I saw it first. So, thank you, Internet user who came up with this before me! The only part I can properly take credit for is using decaf.
Please note that I could not have implemented these ideas without having first consumed coffee, as it is required for brain function.