Writing good XSLTs is heavily experienced-based. I also did not find any XSLT-patterns resources until now.
I learned XSLT on the Mulberry XSLT list. That's a very good resource with the best XSLT-writers offering their help: Michael Kay, David Carlisle or Jeni Tennison, but learning from a mailing list, i.e. by other ones' use cases, is of course very time consuming.
From that list I know that Jeni Tennison is a very good explainer and I heard her books are good as well. She has one book for beginners and one for advanced users. Michael Kay's reference is also recommendable.
Furthermore there is a FAQ on XSLT maintained by Dave Pawson, which is more or less a Best of Mulberry XSL list, but you need to know what to search for.
An excellent XSLT Tutorial in several languages on ZVON.org
Helpful XSLT Patterns (German only) on http://infos24.de