Some Danish dialects do some weird things with high vowels with stød. In a lot of places these changes got, or are getting fully or partially reverted though. Source is
http://jyskordbog.dk :
Midvestjysk + Sydfanø + Rømø (also Sydsamsø and Vesthimmerland, though with unlabialised k, and only in codas):
iˀ yˀ uˀ > ikʲ ykʲ ukʷ
In Vesthardsysselsk (subdialect of Midvestjysk) also usually: eˀ oˀ > ejkʲ owkʷ (øˀ > øjkʲ only sporadically, or not at all)
The vowels with stød are historically long, Rømø also has a somewhat similar development for long wowels without stød:
iː yː uː > iɣʲː yɣʲː uɣʷː (> Vŋː / _N, no length in codas)
Thy and Mors have iˀ yˀ uˀ > ix yx ux (possibly ç after i, y)
Vestsønderjysk (unconditionally) and Vendsyssel (/_{s,#}) have iˀ yˀ uˀ > itʲ ytʲ uk
All the unconditional changes affecting the vowels with stød have following schwa-insertion except in codas and possibly before /s/.
I wonder if this is at all related to the changes in Faroese posted by Magb:
Magb wrote:Faroese has a pair of sound changes that are very roughly:
Ø > ggj / V[+long][+front]_#
Ø > gv / V[+long][-front]_#
Examples: oy > oyggj, trú > trúgv
<ggj> is pronounced [dʒː].