Show your friends that you have no problem hitting the next big age: Copy an old picture -- maybe from your senior year, big crunchy perm and all (this was my high school cheerleading shot!). Cut out letters from a magazine to write a funny, scrapbook-style caption and glue the picture to a plain note card.
Send each guest a card with a different fresh herb attached: Punch small holes in the top of plain note cards and thread a sprig of fresh rosemary, thyme or tarragon through the holes. Ask guests to bring a dish made with whichever herb is on their invitation.
Write the party details on a blank CD with a fine-point permanent marker. Ask guests to fill the CD with their favorite songs, then send out the disks in CD mailers (staples.com). You'll end up with a whole night's worth of groovy tunes!
Remove wine labels (place bottles in hot water for a few minutes, then peel them off), make color copies and glue them to index cards. Fill out the backs with party details and address them like postcards. Make extra cards with each label so guests can make tasting notes at the party.