Collection of SharePoint webparts - Sites and places

 ‎http://www.dundas.com - Primarily chart and KPI webparts  

http://www.amrein.com/sharepoint - A collection of various useful webpart, Image Rotator etc..

http://www.boostsolutions.com - Administration, BI, Collaboration, Content Management and Security

http://www.bamboosolutions.com - Many useful webparts and solutions available to 2007, 2010 and 2013

http://www.virtosoftware.com - Administration, BI, Collaboration, Content Management, Workflow, Bulk Operations and Project Management

http://www.pentalogic.net - A small collection of webparts you might find useful. Team Time - if you looking for a Punch Card/TimeSheets solution

http://www.kwizcom.com  - Many useful webparts and solutions available to 2007, 2010 and 2013

http://www.lightningtools.com

http://www.layer2.de

http://www.codeplex.com - Opensouce projects/webparts, with very different functionality, workflow add-ons, powershell scipts ect...

http://www.harepoint.com