Can any one help with ideas for a 21st invite?

Need help with a design for a 21st invitation. There is no theme for the party, colour theme for the invite is black, pink %26amp; silver. I am looking for a unique/individual idea. Any suggestions would be appreciated. Thanks
Can any one help with ideas for a 21st invite?
Black card for background, with pink balloons on cover... have the balloons as cut outs, that split in the middle to open out and have the invitation details written in silver 'underneath' each balloon.





Have a trail of silver ribbon or silver puff paint leading down from each balloon and tied together in one corner..





When cutting the black card for the backing piece, measure to fit the envelope you want to use, then allow an extra tab, that you can score well and fold back behind the front of the card, on the bottom. This will act as the RSVP, so all your guests have to do is fill out their name and tick either acceptance or non acceptance, cut on score line, and post back to you.