Some of my books are about walk-in angels. here are some links (feathers) to provide you all you ever wanted to know:

http://innerself.com/Spirituality/angel_9262.htm

http://www.angelsghosts.com/angels_messengers_ghosts.html

http://www.circle-of-light.com/Angels/angels-info.html

http://www.spiritual.com.au/angels.html

http://angelstoday.net/index.php?lang=en&way=1information

http://www.greatdreams.com/walkin.htm