Chianti and other Tuscan wines are famous all over the world. Visiting Tuscany in late August-early October you can see how it's made and even participate in the harvest. Go to Chianti or Montepulciano and try a stay at a farmhouse and enjoy the simple life of local farmers volunteering to help. World Wide Opportunities on Organic Farms lists 30 vineyards in Tuscany that seek helpers. Experience is not required, bed and food are usually provided. And you can enjoy excellent Tuscan wines as a bonus. If you prefer to take a guided excursion rather than work, several operators offer Vendemmia Tours that includes a two-hour harvesting experience and lunch.
Working side by side with farmers to hand pick grapes may be one of your most memorable experiences in Tuscany. Along with the work, the harvest is a time for celebration, so lots of food, wine tastings, and music are guaranteed as well. But make sure you apply in advance as many Italians living in cities take time off to help with grape picking, so competition is pretty high.
Vendemmia is the perfect time to tour Tuscany's most famous vineries. In North Tuscany, you can visit Capezzana and Castello di Nipozzano. In Chianti, it's worth checking on Castello di Ama and Antinori. In southern Tuscany, there is Bolgheri Wine region with such vineyards as Le Macchiole and Riparbella. In Meramma area, there are also many smaller vineries like Fattoria La Maliosa in Saturnia and Vino Montauto in Manciano, holding regular tours during Vendemmia.