Then there are the Xenu saucers that froze and accumulated debris around Saturn
http://www.space.com/scienceastronom...urn-moons.html

They always go the wrong way...
http://www.space.com/scienceastronom...-way-halo.html

From fiction...
http://www.arapress.com/saucer.html

The real things
http://www.astronautix.com/craftfam/lenicles.htm
http://www.cartechbooks.com/vstore/s..._ID=1602&DID=8

The source of contrails by Air Force bases--captured versions of these:
http://www.specialtypress.com/vstore...D=1713&CATID=1


Cooler than cool
http://www.specialtypress.com/vstore...D=1706&CATID=1