Absinthe, often referred to as the Green Fairy, is a potent distillate of wormwood, green anise, and fennel. The flavor of absinthe is dominated by fennel and anise, and it appears either pale green or clear (though a rouge style was also once produced). Famously alleged to have psychotropic effects, absinthe was banned in several countries in the early 20th century. But recently absinthe has become available for sale for the first time in years, and this should be a cause for celebration: we are once again free to enjoy its flavors and dispute its effects.
Absinthe was the unofficial beverage of Paris during its cultural renaissance at the turn of the 20th century. Ernest Hemingway, Oscar Wilde, Vincent Van Gogh, Henri Toulouse-Lautrec, and Edouard Manet are among artists who featured absinthe in their work, and likely contributed to its reputation for hallucinations.
The disputed effects of wormwood can be attributed to the presence of thujone, a convulsive agent (though not a hallucinogen). The U.S.'s federal ban on absinthe was based on its levels of thujone. Recently it was discovered that levels of thujone in some absinthes are low enough to be safe for consumption. Currently, individual brands of absinthe must be approved on a case-by-case basis, so don't go stocking up on it next time you're in Switzerland; the customs agents may very well confiscate it.
The ongoing cocktail revival that is sweeping the country has embraced the reappearance of Absinthe, and well it should. Absinthe is an integral part of many classic cocktail recipes, and real absinthe can now replace the common practice of using pastis or anisette as a substitute.
However, consuming absinthe on its own is well worth it: a high-proof distillate (not a liqueur, as it is often mistaken), it contains subtleties and nuances not often associated with its anise-based siblings. Traditionally, absinthe is to be gently diluted with cold, clean water and sweetened with sugar. Because absinthe is an extract, dilution was found to not only mellow the drink, but also to allow the less assertive flavors to blossom. Furthermore, gentle, slow dilution was recognized to draw out these nuances more effectively, and so the use of a fountain was developed. The absinthe fountain does not in fact contain absinthe; rather, water, which pours out in narrow streams from multiple spouts over the sugar cubes that sit on slotted spoons atop the glasses.
Some of the new absinthes available today are already quite sweet, whereas others are less so. Taste them for yourself - there are no rules or regulations regarding proper consumption. That being said, there are rituals, and certain practices today are disparaged by aficionados--the dramatic habit of lighting an absinthe-soaked sugar cube (or the undiluted spirit itself) on fire can probably be attributed to the Flaming Sambuca (circa late 1980's), where a shot of Sambuca is lit and then quickly extinguished before consumption. Absinthe experts tend to ridicule this technique, condemning it for altering the flavor of either the liquid or the sugar, or both. Some brands worth trying include Lucid Absinthe Supérieure (made in France by the New Orleans chemist and absinthe expert Ted Breaux), Kübler Absinthe Supérieure (Switzerland), and Taboo (made by Frank Deiter in British Columbia, Canada). No matter what you and try and how you try it, it will be a drink worth taking.