UI Design Patterns: http://ui-patterns.com

Peter Morville's Findability: http://www.flickr.com/photos/morville/collections/72157603785835882/

Brian Christiansen's collection of patterns:
http://www.flickr.com/photos/factoryjoe/collections/72157600001823120/

Barbara Ballard/Little Springs Design mobile patterns wiki:
http://patterns.design4mobile.com/index.php/Main_Page

Janko has a great post on Table UI patterns:
http://www.jankoatwarpspeed.com/post/2010/02/26/table-ui-patterns.aspx

Mephobox is a series of pattern collections but this one's more for inspiration and less about good patterns with usability in mind:
http://box.mepholio.com/ By Jasmin Phua