You could also plug-in or recored a shortwave radio for the the lovely Sputnik style sounds, I keep a bunch of samples of that on a Radio Music or Disting.
Ive not done it for a while but I've used snippets of samples triggered by short envelops to be used as evolving percussion sounds.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.
Sweelinck and EuroBadger