When working on a recent post, I came across a little bit of trivia: rack vs wrack.
Particularly interesting was this item: http://grammar.about.com/od/alightersideofwriting/a/rackwrackgloss.htm
Though the general advice of linguists appears to be to use the form Rack and Ruin or Nerve-Racking, I chose to use the form Nerve-Wracking. The reason is simple; rack is an overloaded verb, whereas wrack is not.
When I think of "to rack" something, I think of organization. Racking billiard balls, primarily. What I don't think of is the destructive term which is primarily associated with the medieval torture device "The Rack". We don't have that kind of rack anymore, so it seems silly to use that as the basis for the modern verb.
Should I wrack my brain, or rack it? The answer seems simple to me: one is [thinking so hard you're] hurting it, whereas the other is [thinking so hard you're] placing it into some kind of organizational box; at least if you go by the primary meaning.
That said, such a rule would go counter to accepting that most people cannot remember when to use "except" versus "accept". I think the linguists have just given up, and are desperately picking their battles, hoping that "sumday were not left wit nuthin but a shell of english that we should of protected".