When you are hosting an event, you want to spread the word, and you wanto to do it as efficiently and cheaply as possible. I know I do. We all know Facebook and all those big monsters, that can be used to send invitations. I am not going to talk about Facebook here, primarily for the fact that I don’t like their policies very much. There are plently of smaller alternatives, that are geared specifically towards making some noise for your event. Use them to send people invites, either to their mailbox, or by snail-mail. Some of the sites even let you rpint out the invitations, and some will even mail them for you.
In any case many of these services offer integration with Facebook, so you can still have use your account there.

• Anyvite seems to be easy to use for creating online invitations. Choose one of the many provided designs for your invitation, or create your own by uploading a picture, searching Flickr, and/or choosing a pattern or color. Use the “Search For Location” link to find possible venues for your event. Public invitations allow anyone who accesses the provided URL to RSVP for your event. Great for large, open events. Lots of features. Both a free and Premium version.
• Crush3r is a free service. Just click the “create event”, and add the geo-location for your event. Wil also let you poll your guests as to when is the best time for the event.
• Enclude is an online invitation and eCard web site without ads. Enclude online invitations are clutter free, classic and easy to customize with your own photo. You can set-up, personalize & send your online invitation in just a few minutes.
• My Punchbowl is free, if you can accept ads. They have a Plus and Premium membership, that cost USD 3 and 4 respectively. You can use them for all kinds of party planning and E-cards, etc.
• Paperless Post is not ad-supported so your invitations will always remain personal and free of pop-ups and ads. Use it to send custom, personalized invitations and announcements with the same thought and care as previous generations, but the way we communicate today: online. Members can send out invitations for any occasion- dinner parties, anniversaries, save the dates. Not free.
• Pingg lets you send online invitations and e-cards for free. They have something called Pingg Plus, which has lots of added features. It seems that Pingg Plus will coast a USD 10 one time fee, and it seems to be worth it, as iot gets you ad-free, and lots of good stuff.
• Purple Trail is a free and ads-free online E-card maker. You can make, and send them online, and them choose to download them and print yourself, or have them mailed to you for an extra fee. They have more than 5,000 designs to choose from, and your guest replies are tracked automatically.
• Sozializr lets you add it all, music, photos, video, flash for free. No ads in the invitations. Seems to be 100% free.
• Zoji provides you with useful tools to help create and manage your group events and online invitations. Group forums, unlimited photo uploading and custom skins are some of their features. They are a free service with no hidden fees and no ads. You can create groups and events and send out email invitations to your friends to attend an event or join a group.