I live in Berkeley, CA and have been enjoying identifying many new birds, but my favorite is the Bushtit. Though not very distinctive in color, they are adorable and rich in personality, tiny butterballs of pure energy. I love how they blow through the yard in berserk little flocks, peeping away and flitting about from shrub to tree for a minute or two before cruising on to new destinations.
I don't have a good pic of my own, so I borrowed this one from the web.