Last week when I looked at databases pools I got a few suggestions re master/slaves databases. In this configuration you set up a single database (called the master) and have it replicate to one or more other databases (called the slaves).
Basically it's a way of marking up HTML to give it more more meaning, think of it as the semantic web (with a small s) that is available now.
hCard is a HTML representation of vCard and while no browers currently support it natively, the next versions of Firefox and IE will support it. There are also plugins currently available for Firefox (Operator and Tails ) and Safari (various bookmarklets) and IE (various favlets).