I have gotten a laugh out of this thread! There has been a ton of stuff we haven't used for DD.
The change table with the bath underneath...couldn't live without the change table but have never used the bath bit.
J&J products - just hell on DD's skin! And that seemed to be the default gift from everyone
Bassinet attachment for Strider Plus pram - DD had reflux and couldn't lay flat.
Feeding pillow, breast pump, feeding bras / singlets / tops - couldn't breastfeed.
Bonds wondersuits - the collars would irritate DD.
Tiny shoes - seriously, who puts these on babies?
TONS of clothes we were given for the wrong season. DD was a winter baby and was too big for a lot of the lighter hand me downs.
Baby carrier - DD just hated it.
There's probably more!