The Sitecore Field Suite open source module contains an "Image Field" control that allows you to attach multiple images to a content item. Unlike a normal multilist, the Image List allows authors to see the images they are attaching directly in the Content Editor, which can be very helpful in choosing and arranging Carousel items.
Links:
- Blog post introducting the Field Suite: http://blog.velir.com/index.php/2012/10/24/sitecore-field-suite/
- FIeld Suite on Sitecore Marketplace: http://marketplace.sitecore.net/en/Modules/Field_Suite.aspx