I don't know of any sites like you describe, unfortunately. If there isn't one then someone should make one!

But fwiw here are a few ways I've pronounced things (hopefully others can correct any mistakes)...
antidoran = an-tid-oran
Chrysostom = chris-sis-tim
Nyssa = nissa
Myra = mira
theosis = thee-oh-sis
prosphora = pros-phor-ah
apokatastasis = apo-kata-stasis
kathisma = ka-thees-mah
kathismata = ka-thees-ma-tah
praxis = praks-is
ascetic = ahscetik
ascesis = ahs-cesis
podvig = pod-vig
prelest = pree-lest
phronema = phro-nay-mah
nous = noose
deification = dee-ah-fah-cation
akathist = ak-ah-thist
A lot of words I sound out just like they're spelled (divinize, consensus patrum, etc.)