Then come the options. Hosts can decide whether to show the guest list and RSVP status to prospective attendees. They can encourage guests to bring friends but also post the maximum number allowed. Guests can give food preferences or choose from a list of dishes automatically updated whenever someone commits to bringing one. That's not all.
Hosts can send reminders to guests shortly before the party.
At Mambo and MyEvents, hosts can set up a message board so guests can discuss the party beforehand. There is something about this hyper-efficient party planning that betrays its Silicon Valley bias, which some may find presumptuous. For one, there is the assumption that all pals have E-mail accounts. In Northern California, where people beam their contact data via Palms, this isn't a problem. But if I were to rely on one of these sites to get the word out about a dinner party on Saturday for 10 of my closest New York friends, I'll bet that half, at best, would show.