ETA: Google suggests the disk error code I'm getting basically means "the disk is about to die." I'd better order a replacement in the morning...
localhost:/ root# /sbin/fsck -fy
** Root file system
** Checking HFS Plus volume.
** Checking Extents Overflow file.
** Checking Catalog file.
disk 0s2: 0xe0030005 (UNDEFINED).
Invalid node structure
** Rebuilding Catalog B-tree.
** The volume Dors could not be repaired.