Photos of many of these projects can be found on the following page,
http://pinterest.com/pinwheelpond/yo-yo-projects/
Click on any photo to see a larger image. A link to the original page will be above the photo.
Lollipop ornament
http://www.happybirdscraftinghaven.com/2008/07/cute-yo-yo-lollipop-christmas-ornaments.html
http://mousechirpy-polkadotpineapple.blogspot.com/2008/07/welcome-to-candy-shoppe.html
Baby Jesus
http://ajpadilla.com/patterns/seasonal/christmas/winter/ornaments/yo-yo-ornaments/sweet-baby-jesus
Santas
http://melzamelo.blogspot.com/2010/10/fuxicopapai-noel-para-arvore-yo-yo.html
http://museumquiltguild.blogspot.com/2009/11/nov-meetingmeet-members-melanie-mary.html
http://store.happyhollowdesigns.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=HHD&Product_Code=599&Category_Code=QU
Yo Yo Christmas Trees (photos and/or tutorials)
http://www.kiwiatheart.com/yo-yo-christmas-tree-tutorial/
http://www.flickr.com/photos/12826779@N02/2130193192/in/set-72157603274312476/
http://www.cddesigns.com/AfternoonProj/YoYo/PDFs/yy002b.PDF
http://www.craftster.org/forum/index.php?topic=136150.msg1336197#msg1336197
http://www.flickr.com/photos/homehooked/3016648154/
http://www.ehow.com/how_4540304_make-yoyo-christmas-tree.html
Yoyo covered balls
http://pinwheelponders.blogspot.com/2009/08/yoyo-pomander-yo-yo-ball-ornament.html
Wreaths (yo yo variation)
http://mousechirpy-polkadotpineapple.blogspot.com/2009/09/merry-yo-yo-christmas.html
Angels
http://www.craftsayings.com/projects/small_gifts/yo_yo_angels/index.shtml
Bell
http://www.favecrafts.com/Ornaments/Yo-Yo-Fabric-Ornaments#
Flat trees (Photos and/or tutorials)
http://lutterworthpiecemakers.blogspot.com/2009/11/annual-general-meeting.html
http://www.spotlight.com.au/inspiration/projects/yo-yo-wall-hanging/
http://ajpadilla.com/patterns/seasonal/christmas/winter/ornaments/yo-yo-ornaments/embellished-yo-yo-tree
http://www.stitcharena.co.uk/try/patch-and-quilt/suffolk-puff-christmas-tree/
http://www.qheartland.com/files/YoYo_Tree.pdf
http://www.familyfarmquilts.com/product.php?productid=1085&cat=229&page=1
Tree from styrofoam cone and yoyos (photo only)
http://www.allpeoplequilt.com/magazines/quiltsandmore/color-options-winter-09_ss6.html
Small wreath from hexagonal yoyos
http://pinwheelponders.blogspot.com/2009/12/playing-with-yoyos.html
Large wreath
http://lutterworthpiecemakers.blogspot.com/2009/11/annual-general-meeting.html