Whats wrong with leopard Disk Utility ? You can resize, format etc, unlesss theres something very specific you want to do.
http://www.creativetechs.com/iq/leopard_disk_utility_can_resize_partitions.html
Im pretty sure that Leopard Disk Utility can dynamically partition a hard drive without losing any data, for example the boot camp assisstant can already do this.
Maybe someone could verify this? as Im not able to.
(this thread seems to show its true http://forums.macrumors.com/showthread.php?t=435855&highlight=leopard+partition+hard+drive )