In congregations that daven with Nusach Ashkenaz, the Friday night Maariv is preceded with a recitation of Mishnayos beginning with the words: Bameh madlikin u'vamoh ain madlikin...
I always wondered why the first במה is vowalized with a segol (bameh) while the second one gets a komatz (bamoh). They both seem to mean the same thing, so why do they have a different nikkud?