Though Internet party planning is hardly a new concept, here are a couple of websites to help you solve a lot of these and many more party-related problems.
http://www.evite.com/ - this one has been around for ever
http://www.mypunchbowl.com/ - this is a new kid on the block… err web
It is straightforward, simple application. With a Pick-A-Date feature that makes the hardest part of the process much smoother. You can try it out or sign up for a free account. They even have free e-cards, you can personalize your invitations or make your own designs
http://renkoo.com/ - Renkoo helps you arrange casual get togethers with your friends. This is a service that lets you arrange when and where to do fun things with friends. You can use the website, instant messaging, text messaging, or email to plan things together.
http://www.socializr.com/ - is a free web service for sharing event and party information with your friends. It allows you to integrate info from networking sites like my space and Friendster into your profile, blogs, Flicker and Youtube. It also provides the tools needed to promote event on your sites. You can personalize your invitations with music and videos, make your own designs and share them.
Have fun party planning