There are many stories about angels... They are said to be of human figure (most oftenly women or young children) with huge white bird's wings, and a glowing halo. The men and women are generally clothed in white robes, and the children are either the same or naked.
Angels originated from the bible, where they were said to be messengers of God. There are some stories of how certain angels turned against God because they felt that He, having given souls to humans and not them, loved humans better. There are many interesting stories of angels in the Bible. More of this can be found in the Angels in the Bible section.
I think that the main person who set for us the image of angels as they are today was Hans Christian Anderson. He wrote a story about angels who bring dead children up to Heaven with flowers to grow in God's garden... It's really quite a nice story, one that you could picture your mother reading to you as a bedtime story when you were five... It can be found in the Fables section. It may have been the first story that gave us the notion that humans become angels when they die. Whether or not this is true I don't know... I suppose I'll have to ask Mathius sometime.
It's also said that everyone has a guardian angel who watches over them in their life and keeps them from harm and evil. Mathius has told me that he is, in fact, not my guardian angel, but that he's met her. Some people say that your gain a guardian angel when your loved one dies. They become your guardian angel, and spend their days watching over you from Heaven.
I find stories about angels so comforting... They make death sound so much less scary. Anyway, that's all for now, check out the other links! ^_^