Wine Enthusiast has some great items. If you like to order on line you can also visit
www.wine.com. The wine vacume that Linda mentioned is a great tool. Some don't like it. They think it makes the wine taste dead.
The killer is oxidation. When I have a red that I've pumped the air out of, I sometimes put in the refrigerator. The cold slows the oxidation. When I'm ready to finish the bottle at the end of the week I pull it out, and allow it warm to about 65F.
A decanter also makes a nice wine gift. Many red wine lovers don't bother getting one for themselves because they think of it as too fancy.