We're big tea drinkers around here and I've found a way to add variety easily. A basic simple syrup is boiling together equal portions of water and sugar. Then you add the fun.
Lemon--Lemon peels soaked in warm syrup for a few hours, and then add the lemon juice too after it's cooled.
Mint--chop a bunch of mint and let soak for at least 4 hours. Strain. I make this at half sugar because mint doesn't need that much sweetening.
Ginger--I wrote about Ginger syrup here and it is a great addition to iced tea.
Vanilla--split a vanilla bean and scrape the seeds into the syrup. Add the pod. Let soak. Remove the pod. Strain through cheese cloth to remove most of the seeds. You can add the pod back into the bottle, if you want.
Lavender--I haven't made this one yet, but the lavender in the garden is just about ready.
We have lemon, mint, vanilla and ginger in chalkboard painted bottles the frig now and we mix and match all the time.