(this page is part of the wiki materials for ApacheAvalon; avalon main page in the wiki is AvalonProjectPages)
Avalon is used in lots of places. Projects hosted at apache that use (parts of) avalon include:
Cocoon - See CocoonProjectPages
James - James
Turbine - TurbineProjectPages
XML FOP - See FOPProjectPages (work in progress and only slowly)
A non-Apache project that uses Avalon (and Fortress) is Keel, at "http://www.keelframework.org"
Also note http://avalon.apache.org/apps/appselsewhere.html has some more links.