Here is a great idea that my husband came across on a site called Digital Photography School.
This past year, we attended a wedding in LA where, during the reception, there was a photo booth. This was pretty fun, very popular, and best of all, the bride and groom were able to view all the pictures later (fyi for all x-rated revelers) and use them for scrapbooks, etc. Well, for those of you who are not so keen on renting a photo booth - how about setting up your own?
Set up an area with a curtain background, good lighting, and a tripod. Put a point and shoot camera set on a timer so people can take pics of themselves. Be creative with props or backgrounds, and you will have unique memories of your special day!
Here is the post, it's item #3.