A lot of cultures have holidays around this time, but did you know that there's an older one that if you're feeling sexy you might be up for celebrating?
May Day, aka Beltane, was an ancient Celtic fertility festival heralding the oncoming summer season. Like Samhain, it was seen as a time when the veils between the worlds were thinnest. What most people know of this festival which survived is the Maypole.
In ancient Rome a festival to honor Flora, a goddess of flowers and vegetation, occurred around this time as well.
In modern Wicca the "hieros gamos" or sacred marriage between the Goddess and God is honored on this day, usually ritually enacted by the High Priest and High Priestess of the rite. Although on rare occasions this will involve actual sex, more often than not a blade being inserted into a chalice is more than sufficient to convey the meaning of the holiday during the ceremony.
Some good links:
Love & Magic,