Wooley Buggers are great at night time too.
Go out at night and the thrill is ampliphied.
Midges,nymphs, oh well,(I wont say dredging 'cause that would sound snobby).
Now lets talk about Dry Flies. Can we say WOW. When you decide to go dry you will catch less but to me its really worth it . There will be hatches in the winter . There are usually hatches all year round. The flies stay in the warmer air at water level and you wont see them very well if at all.
There are sections on this site that discuss winter fly fishing.