Cruft is clutter that bogs things down and gets in the way of getting things done. Idea clutter is mostly stuff that we could have gotten rid of to begin with. When you initiate an activity, determine a kill date for it at the same time.
Concrete ideas to modify and expand this hack go here.
There are tools that delete files in the /tmp directory if they haven't been accessed in a user-specified amount of time:
Freeform discussion of this hack goes here.
Errata go here.