I use this in tomato sauces, beef or veal stew, pot roast, anything in which you otherwise might use a red wine. It is an Italian fruit condiment made from cooked, reduced, unfermented grape must. It's the same stuff that, if fermented, would become balsamic vinegar. It is very thick and sweet enough to eat on ice cream, although I haven't tried that. It adds a richness and taste that I really can't describe. Pricing varies wildly on the Internet. When a local store temporarily stopped stocking it, I saw ridiculous markups on the Net -- up to triple what I'd been paying. This is where I turned, and it's still a fair price:
http://www.ibfoods.com/store/item.asp?ITEM_ID=840&DEPARTMENT_ID=123