I signed up for www.centerd.com and have found that it makes planning "anything" from a party to traveling a cinch.  The reason is that it is an easy to use online tool that allows you to share responsiblities, track who has completed their item, add items, and it easily (one button) imports to you personal calendar.  It also lets you search by location for recommended places ... to eat dinner, host a party, etc ... 

I recommend that anyone who likes to share information, plan parties and find ideal locaitons join the fun.