WeddingWire posted a recent blog that had three gorgeous ideas for altars!
The Chalkboard Backdrop
Though you could put whatever you want on the board, I love how this couple highlighted their families--such a sweet idea to honor those close to you!
The Floral Arch
Okay, while the test tubes look kind of cool anyway, the actual idea behind this is awesome--prepare flowers with pre-tied tags on them, allow guests to pick a flower and write their well wishes on the tag, and then before the ceremony, they place their flower in one of the test tubes. This way you have the wishes and thoughts of your guests with you as you become husband and wife!
The Doorway Arch
Everything about this set up is so beautiful (even the altar in the front of the ceremony space). However, what steals the show are the doors, signifying the new chapter in the lives of the bride and groom. However, I think it's a cool idea if you can get the doors to close and then open with the bride enters, allowing for the big reveal that you get in an indoor wedding to be replicated outdoors.