Millesimi is an enoteca on Borgo Tegolaio, a little street near Piazza Santo Spirito. It is a "fine" wine shop, featuring the best of Tuscany, and also an impressive selection of European wine, including both still French wines (maybe the best I have seen in Florence) and Champagnes (I believe the owner is French and sources the wine directly). If you are a wine lover and are in Florence, this is a shop you could (and should) spend an hour or two browsing around in.
Borgo Tegolaio 33/r
Tel. 055 2654675
Email: firstname.lastname@example.org (you can email them to place orders)