I had a lot of Next tasks, which were getting overwhelming whenever I looked at the list. At the recommendation of someone on a GTD site I moved every task that I'm not working on right now or in the very near future to Someday. This keeps me much more focused. However, now Someday has become a huge list, and I feel that items like "learn to play guitar" don't belong in the same category as "set up bed for friend who's coming to stay in two weeks".

It would be really useful to be able to subdivide my Someday list into multiple other lists, or add a general customizability feature for the focuses. I would prefer not to use tags, as I would have to remove these when turning my Someday items into Next items. (This would also provide a solution to what http://help.doit.im/topics/390 was asking: move the non-next items into Someday - Weekly or Someday - Monthly, keep the "original" list of Someday actions uncluttered.)