GO visit the South Face of Lone Pine Peak. Things like the Winter Route and the more difficult Winter Chimney are awesome. I tried Dyanamo-Hum (the HUGE corner system) last winter. We made up to the massive roof via ice, mixed and rock climbing but it had gotten too warm and by mid-day and everything started falling down so got the hell out of there. I think we waited too long in the season. There was definetly some ice up there though - would have been spectacular at the top.
The Sun Ribbon Arete on Temple Crag has been done in the winter. It's likely that it hasn't seen one since- this looks exciting & extremely interesting!
SP's own Misha (& Pavel?) did the E ridge of Russell in either the winter or spring- this looks challenging & fun too.
Long Valley, used to access Bear Creek Spire in the summer, is frequently skied in the winter- there are numerous peaks lining the valley- don't know the difficulty or avalanche danger on those slopes, but access is less of an issue than with other areas (the chief detractor from winter climbing in the Sierra, I'd say).
Yosemite Valley or Glacier Point road are excellent access points for higher locations in the winter, due to the lack of access restrictions (i.e. the roads are open to get there).
Don't know where you are, but Shasta & Lassen also make great winter climbs, conditions permitting.
Here is a list of the highest peaks I've climbed in the winter:
White Mountain Peak
Norman Clyde Peak
I climbed the technically easiest routes on each peaks except for Sill, Polemonium, North Palisade, and Thunderbolt, which I did from the Palisade Glacier.