I trawled the Knytt level release board, looking for dead links to levels not already on knyttlevels.com (to the best of my knowledge). This is what I found:
A Hidden Esper Channel -DataflashsabotThanks jeanbeane
relevant topic (http://nifflas.lpchip.nl/index.php?topic=804.0)
Game of Depressions -Terzom/Jane_Brain
relevant topic (http://nifflas.lpchip.nl/index.php?topic=836.0)
"Boss Pack" - Razor
relevant topic (http://nifflas.lpchip.nl/index.php?topic=978.0)
Cat -Isnoct
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1008.0)
Cat 2 -Isnoct
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1018.0)
A Few Problems -Dataflashsabot
relevant topic (http://nifflas.lpchip.nl/index.php?topic=565.0)
escape the cube -bunnrey Thanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1320.0)
Summer and winter -Dandelion
relevant topic (http://nifflas.lpchip.nl/index.php?topic=833.0)
Break Time -Emeraldfire7Thanks jeanbeane
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1979.0)
The Sound of Snow -gunpowderteaThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1951.0)
Nightly Symphony -Zetta
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2564.0)
The Sunken Castle -Freddieboj (did anyone snag before the mod edit?)
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2689.0)
(COtest) Birds in the Rain -FirecatThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2765.0)
Water World -LBThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2772.0)
(Tutorial) Both Warps -Bored2death
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1366.0)
No Trespassing -Lizzaroro
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2922.0)
Spacial Thought Chapter 1 -radonschism
relevant topic (http://nifflas.lpchip.nl/index.php?topic=2667.0)
Soothing Pains: Solar Confliction -Lavishly Lazy
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3053.0)
The World Below -shawnachuThanks egomassive! DLMirror (http://levels.egomassive.com/levelsbin/shawnachu-TheWorldBelow.knytt.bin)
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3034.0)
Order a pizza! -Razor
relevant topic (http://nifflas.lpchip.nl/index.php?topic=787.0)
Pink Juni -SalmoneousThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3108.0)
Frozen Forest -DandelionThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1743.0)
Squeaky Clean -GliblordThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3317.0)
Back to the basics -Lizzaroro
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3458.0)
the icy mountens -rpg
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3480.0)
Midnight Rainstorm -BeeZeroOne
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3054.0)
Tom's bossrush -Lizzaroro
A nice day for a walk -Lizzaroro
relevant topic (http://nifflas.lpchip.nl/index.php?topic=859.0)
(beta)Pokeknytt -FlyingPigBoyThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=3344.0)
Kill Kitler -googoojoobThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1746.0)
Darkness -Pick Yer PoisonThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=1377.0)
Depths -Emeraldfire7
relevant topic (http://nifflas.lpchip.nl/index.php?topic=4323.0)
K's world -KramsysThanks egomassive! DL
relevant topic (http://nifflas.lpchip.nl/index.php?topic=4418.0)
Pure Pulse Adventure -60FourMaster
relevant topic (http://nifflas.lpchip.nl/index.php?topic=4398.0)
?placehold? -SingingSurgerThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=4835.0)
?CoCo? -Declivever
relevant topic (http://nifflas.lpchip.nl/index.php?topic=5002.0)
Kezionay -SingingSurfer
relevant topic (http://nifflas.lpchip.nl/index.php?topic=5170.0)
Chatboxx -SingingSurgerThanks yohji!
relevant topic (http://nifflas.lpchip.nl/index.php?topic=5171.0)
General Edit 1: Thanks jeanbeane, and apologies to dataflashsabot!
Anyone happen to have any of these hanging around on their hard drive, and able to upload to knyttlevels?