Resources: SharePoint WebPart(s)

Adding Group and Quick Add Groups to your custom webpart programmatically 

SharePoint 2007 & 2010 development: How to remove a bad webpart from a page?

Problems with webpart after webpart is upgraded using Stsadm & Upgradesolution

Let the SharePoint Search web parts use an other Ranking Model

QueryStringPageViewer WebPart for Sharepoint – Mads Nissen

Inconvenient programmatically exporting Web Parts – Waldek Mastykarz

Programmatically Add ListViewWebPart with Customized View | Of Ones and Zeros

Stefan on SharePoint | Add Web Part to Page Programmatically

Quick Tip: Provisioning Web Parts to a Page – The SharePoint Guys – Site Home – MSDN Blogs

How the XsltListViewWebPart in SharePoint 2010 can be a real performance killer « Jaap Vossers’ SharePoint Blog

How to Add Web Parts to the Page Programmatically | Salaudeen Rajack’s SharePoint Diary

WebParts | Ketul’s Weblog

Presence Indicator:

sharepoint – Adding presence indicator to a custom web part – Stack Overflow

How to Display Presence Indicator in Custom Webparts « ahmedmadany

How to add Microsoft Office Communicator user presence icon to custom page/web part in SharePoint

Enabling Presence Information in SharePoint with Microsoft Communications Server 2010 – Programing4Us – Enterprise

Content Query Webpart – CQWP:

Formatting the Content Query Web Part and Removing HTML tags

SharePoint: Customize Content Query output with XSLT

How to: Display Custom Fields in a Content By Query Web Part

How to: Customize the Content By Query Web Part by Using Custom Properties

CQWP does not display list with custom datasheet

Extending Content Query Web Part with custom data – Waldek Mastykarz

Customizing the Content Query Web Part and Custom Item Styles