Many many ages ago I took a German class … the instructor said that the ü sound had no equivalent in English and we spent some time in class learning how to make that particular noise … it was of critical importance since this noise is very very close to how the word ich is pronounced … the closest we find in English is how a Scotsman would pronounce the word “loch” as in Loch Ness for the ö noise … I think it’s called an unstopped labia minora, but I could be wrong on that point …
Perhaps. When I studied the lingual arts I think we practiced with those labials just before the fricatives, plosives, and liquids.
Yes. In Polish o represents the vowel in “hot” while ó represents the vowel in hoot.
You just ninjaed me to it. I like how in Polish vodka becomes wódka, pronounced VOOT-ka. Wouldn’t you rather drink something called vootka? It just sounds better.
How many [del]Pollacks[/del] people-with-knowledge-of-Polish does it take to [del]screw in a lightbulb[/del] answer a question? 
It also looks like:
- Some dialects of Kashubian language (in Poland), Ó is /u/, though it’s more typically /o/
- Livonian, a mostly extinct Baltic language, uses ȯ for the /ʊ/, which probably isn’t exactly what the OP wants (oo in hook), but is pretty close.
- Upper Sorbian, a Slavic language in Germany, uses ó for /uʊ/
Malagasy (in Madagascar) uses the letter O to represent the sound /u/. They use the O with a circumflex to represent the sound, for example, “rope” (which isn’t really present in careful pronounciation of the prestige dialect, but occurs in loanwords, coastal dialects and slangy pronounciation).
Okay, I had no idea this would be replied to this much, but yes, I meant diacritical marks by accents. I guess I wasn’t thinking about it, sorry. And also, I wanted the oo sound from words like food, you, and dude. Not like book or look.
The movie “Blood Diamond” is known for depicting the word “bro” as “bru”.
I am not sure how accurate this is, but it's there.That’s what we do here. Welcome to the SDMB. I was even thinking of mentioning a Thai form like
อูฐ (/u:t/), meaning camel
The first symbol looks like an ‘O’, is sometimes transcribed as ‘O’, but is a glottal stop. Underneath that ‘O’ is a symbol (looking a bit like ‘u’) which changes the word’s pronunciation from ‘ott’ to ‘oot.’
But since that underneath-symbol is a vowel rather than a diacritical mark, I resisted the temptation to mention this. 
BTW, the very complicated marking underneath the second consonant in this Thai word for camel is neither vowel nor diacritical mark, but simply part of that (rarish) second consonant.
… as any Kipling fan would know.
South Asian languages must have a common origin for their word for camel, because Hindi has ऊँट, which the colonists pronounced /ʊnt/, oont, O the Gawd-forsaken oont! ’E’s a devil an’ a ostrich an’ a orphan-child in one, because Kipling laid the eye-dialect on thick in those barrack-room ballads.
It’s accepted as an English word, now, because of that history of colonialism, getting in the same way as khakis, nabobs, and endless amounts of curry.
Hindi ūnṭ and Thai ut both derive from the Sanskrit word for camel, उष्ट्र uṣṭra. The same Indo-Iranian root is in the name of Zarathustra: ‘golden camel’.