The following pages have lots of patterns/links to patterns for
variously sized ponchos. Perhaps you'll find one you like.

http://www.crochetpatterncentral.com...ry/ponchos.php

http://faerycrafty.blogdrive.com/archive/140.html

Kelly the Yarn Junkie

Pensieve
A Harry Potter List for Adults
Low Traffic - High Quality
http://groups.yahoo.com/group/pensieve