If you're having a destination wedding, then all of your guests will be traveling in from various locations. You're too busy being the bride to play travel agent, so a wedding Web site could be a place to post pertinent travel details, such as hotel information, local dining options and other fun things to do during wedding downtime.
Even if you have the wedding in the city where you live, you'll probably be inviting some out-of-towners. If you have important details that you don't want clogging your invitation, a wedding Web site is a great spot to share them. An easy way to get the word out is to include the Web site URL on an insert that gets mailed with your invitation.