Rich syrup, 2:1
Twice the sugar to the same water. Sweeter per spoonful, so you add less liquid to a drink, and it keeps considerably longer.
No heat at all
Equal parts in a jar, shaken hard every few minutes until clear. Takes ten minutes of nothing and avoids the pan entirely.
Demerara
Molasses and toffee rather than clean sweetness. Suits anything dark — cola, coffee, a spiced drink.
Honey
Three parts honey to one part warm water, or it is too thick to pour cold. Floral, and it takes over a delicate drink.
Herbs
A handful of mint, basil or rosemary in the warm syrup, left twenty minutes then strained out. Any longer and it goes grassy.
Citrus peel
Long strips of lemon or grapefruit peel, no pith, in the warm syrup for an hour. The oils come out, the bitterness does not.
Spice
A cinnamon stick or a few cloves, steeped as it cools. Taste as you go — spice keeps getting stronger while the syrup sits, and it is easier to add another stick than to take one out.
Ginger
A thumb, grated, simmered in the syrup for ten minutes and strained out. This is the base of a ginger soda — and with honey instead of sugar it becomes honey ginger syrup.
Vanilla
One split pod per 200 ml, scraped, seeds and pod both, dropped into the syrup as it cools and left in the bottle afterwards. It keeps developing for about a week and then holds. This is the syrup an espresso martini asks for, and a spoonful in coffee or over fruit is worth the pod on its own. Extract works and tastes flatter — half a teaspoon per 200 ml, stirred in cold, and add it after the syrup has cooled or the flavor cooks off.
From Scratch
