partitioning a partition
 

One final question:

Can you partition a partition (without affecting data on the other partitions)? And will those new partitions be the same as if you had made them in the beginning (so they are fully bootable, etc).

This would be nice for people with large externals that are not sure how they want to partition the whole thing at the beginning (like me). Thanks.

You can't partition a partition, as such, but you can repartition a drive. Disk Utility cannot do this non-destructively (except in some situations, see Boot Camp), but iPartition from Coriolis Systems can.

VolumeWorks will also allow you to dynamically repartition a drive without loosing the data on it. VolumeWorks will even defragment the disk if necessary to allow for shrinking of that partition.

There you go, Chris -- an alternative to iPartition, straight from the horse's mouth @ SubRosaSoft!