Golden syrup is a syrup made from raw sugar which is charcoal filtered to ensure its light blond appearance. The flavor is complexly mild with distinct notes of caramel and butterscotch; despite its low sodium content, golden syrup has a definite salinity to it as well, and makes a superb replacement for corn syrup. For those of you bakers and candy makers, golden syrup is part sucrose and part invert sugar, so it won't crystallize; it offers similar stabilizing properties as corn syrup, but with a richer, more rounded taste. Of course, it's more expensive as well, so only use it when you will be able to taste the difference.
Louisiana produces its own version, cane syrup, by reducing and filtering pure sugar cane juice. If the syrup-making process continues, we have various stages of molasses; the darker the molasses, the more it has been caramelized. Eventually, the sugars will become so caramelized and brown that they syrup will be more bitter and complex versus sweet (as in black strap molasses). A similar process is used to make true caramel color, which colors your colas brown and has no sweetness whatsoever.
Golden syrup is popular in the UK and in Australia as well as in some parts of the American South, where cane syrup and, of course, molasses, are widely used. In recipes calling for golden syrup, you can substitute light corn syrup with a touch of molasses mixed in, but it still won't be quite the same. The flavor of golden syrup is simply unlike anything else.
Although molasses is relatively easy to find, locating Golden syrup can be a bit of a challenge locally - lucky for me, Whole Foods recently discontinued it and I snatched up 4 tins at half price. I have purchased it before at the Fresh Market on Bethel Road, and, for some reason, it is also carried at the German Village Giant Eagle (only that location, which has an interesting selection of international foods all-around, given its small size). Golden syrup can be ordered online through the English Tea Store; cane syrup can be purchased through Pure Cajun Products (I have never ordered from either of these companies, just for the record).
Source for this post: Harold McGee's fantastic On Food and Cooking.