Actually, I have two.
A. Birds "heard" but not seen.
Little Tinamou
Undulated Tinamou
Slate-colored Hawk
Crested Guan
Mountain Quail
Gray-breasted Crake
Tropical Screech-Owl
Mottled Owl
Toucan Barbet
Choco Toucan
Spillman's Tapaculo
B. Birds seen by others in a group I am with, but I "missed" it.
Cinereous Tinamou
Savanna Hawk
Blue-and-yellow Macaw
Red-bellied Macaw
Rufous-breasted Hermit
Green-and-rufous Kingfisher
American Pygmy-Kingfisher
White-eared Jacamar
Golden-olive Woodpecker
Strong-billed Woodcreeper
White-shouldered Antshrike
White-backed Fire-eye
White-shouldered Antbird
Brown-capped Vireo
Lawrence's Thrush
Bay Wren
Song Wren
Rufous-naped Brush-Finch
Tricolored Brush-Finch
Masked Crimson Tanager
Paradise Tanager
Beryl-spangled Tanager
Purple Honeycreeper
Grayish Saltator
Crested Oropendola
Until recently it had to be Pechora Pipit. I was at that stage where the whole world was plotting against me by inventing this crypto-species " Pechora Pipit ". I finally belted up to the Northern Isles ( after giving up twitching - honestly ) and managed to connect with one - then a second bird appeared 
At present I suppose my most exasperating birds will be those that are endemic to areas of the world that are best described as a bit "iffy".
Looking through your list there are a couple that would make me rather bitter. Dipping on Paradise or Beryl-spangled Tanagers when others in the party had seen them is a good reason for going 'total biscuit' ( two levels above crackers!!!!!! )
Chris