Red Admiral butterfly (Vanessa atalanta) on eucalyptus bark. To see what this species looks like with its wings open, review the post from 25 November 2012. I only saw one admiral on 4 January 2013.
Monarch butterfly (Danaus plexippus) sipping from wet mud. Note the long tapering proboscis arching down to the ground (just in front of the eye). I saw at least 4-5 Monarchs on 4 January 2013. For more about overwintering Monarchs, see the post from last February.
Variegated Meadowhawk (Sympetrum corruptum). You can read a little more about Variegated Meadowhawks in the post from 16 August 2012. They're not common in winter, but can be seen year-round in California. I saw two individuals on 4 January 2013.