Perhaps you could sell them cheap, since you got a good deal on them? Think of it as a way to pay the benefit forward.
Looking over your list again, I would also suggest you get rid of:
DT990 -- because you find other mid-low end pairs to be equal or better
Logitech H800, UE6000, and the Turtle Beach -- get a single, wireless, gaming headset that could replace all of these. I use the Skullcandy PLYR1 on my PC and Xbox and it's great. Jude (Head-Fi founder) loves it too.
All your in-ears -- except for 1 sport pair (for, well, sports!). Those IEMs you got all seem pretty average; I think you'd be much happier with 1 really good pair. Maybe the Westone UM3X, or Sennheiser IE80?
Personally, I'd try to reduce everything down to 3 pairs:
1 IEM for sports, 1 closed for travel, 1 non-portable for home use (doesn't matter if closed or open, as long as it sounds great)