For many writers when they hear the words 'multi-author book signing', the first thing they think is 'competition'. While it may be true when it comes to signings with a lot of authors, you can turn that 'competition' into a benefit if you team up with one or two other authors. You can join ranks to promote the event, thus help each other.
And it is a lot more fun than sitting a by yourself at a table.
Create a brief video through Animato and post it on your website, blog, and Facebook, featuring the team of authors.