Wow... I've never had over 50 domains! I can see where you're coming from with that many, but for smaller fry like myself each domain does have an intention. I launched 4 sites this year. Just have to get to the rest when I can. :)
I have a business associate, I gave him the speech this past week about domains which will never be developed. Found out he was hording about 300 domains all related to a single project we're working on and already launched. Only a handful where the typos we needed to catch and a couple of trademark issues. His excuse was "they are all sub-themes of the main site." I had to drill into him that it was bad to put each sub-theme on different sites since they are all part of the "main" topic and it was better to lump them together for greater content on a single domain.
He *promised* he was going to let them expire... but I honestly think some people are somewhat addicted to registering every thought that goes through their heads!