If you routinely plan events, you may find that SignUpGenius can help make the execution of your plans easier. Using the its five-step wizard you can create a variety of electronic sign-up sheets to email to potential attendees.
Features include colourful themes for your invitations, detailed sign-up item list, and the ability to send out reminder emails before the event.
I usually use Facebook to setup events, but I like the sign-up item lists and themes. It would be nice to have these functions added into Facebook. Until then, SignUpGenius is a free ad-supported webapp that just works. It's nice to know exactly who is bringing what so you don't end up with four batches of mac & cheese.