Funny this question should come up today. I was looking at the 20 odd house finches at my feeder today and lementing the lack of purple finches this winter, when one landed on the feeder beside the house finches. Having not seen one for a year, the first thing that struck me was the overall "sparrow dipped in raspberry juice look". It doesn't just have red areas, but has shades of red almost everywhere. And in many cases, such as the first one linked by Jan, the male has that slightly crested look to it as well, as did my bird this morning.
Scott