Check out this awesome little accessory I found while surfing the web!
This little add on is a leather wine bottle holder that fastens securely to the top tube of your bike. The leather straps hold the front and back of the wine bottle and place so you can ride around with out a worry!
The design seems to be nice and well made. The company who makes the product is called fyxation, but I'm sure you could find an alternative to the one shown here. The holder doesn't only work for wine bottles, it will work for most round 750ml bottles.
It looks pretty sharp if you ask me, but I don't know how much I would actually use it. What are your thoughts?