Name the many references in different contexts in Halacha to snow?
- Whether a frozen mass of it can constitute the wall part of an eruv demarcation. (Aruch Hashulchan או"ח שסב:טו)
- Purges sins. (See the Gr"a on "לא תירא לביתה משלג".)
Can it be used to cover blood after Shechitah Can you toivel or your Keilim in a snow drift
- Does snow invalidate the shach of the sukkah? The Aruch Hashulchan says probably: http://he.wikisource.org/wiki/%D7%A2%D7%A8%D7%95%D7%9A_%D7%94%D7%A9%D7%95%D7%9C%D7%97%D7%9F_%D7%90%D7%95%D7%A8%D7%97_%D7%97%D7%99%D7%99%D7%9D_%D7%AA%D7%A8%D7%9B%D7%98
And from the same section of the Aruch Hashulchan:
Is snow considered to be a roof for the laws of tum'ah?
Snow is not m'kabel tum'ah.
Not quite Halacha, but the string changing color to white as snow on Yom Kippur to show that atonement for the Klal was successful .
btw: this week yutorah.org has featured this week http://www.yutorah.org/lectures/lecture.cfm/740735/Rabbi_Mordechai_Torczyner/Snowball_Fights_in_Jewish_Law_and_Thought
An important Shiur on all things Having to do with snow a VIdeo Here Chopping on shabbos,salting,Shoveling and snowball fights Here:
Ben Ish Hai S"B Yito 11 permits people to walk on snow on Shabbat. [Also, later on he discusses if you allowed to mush snow into a cup of water to make it cold, and prohibits it (as well as S"A O"H 320- and Alex's answer). ]
Shulhan Aruch (ibid.) prohibits the crushing of ice, however, permits the placing of it in a cup to make things cold (also see for lengthy discussion the aforementioned BI"H and later on in that Parasha).
See also the Mefarshim on that S"A.