This Web Cast is a good introduction:

http://go.microsoft.com/fwlink/?LinkId=32651

MSDN Webcast: The Power of the Data View Web Part – Level 200

Start Time: Thursday, August 26, 2004 1:00 PM (GMT-08:00) Pacific Time (US & Canada)
End Time: Thursday, August 26, 2004 2:30 PM (GMT-08:00) Pacific Time (US & Canada)

Thanks to Simon Mourier's WebLog for this:

http://blogs.msdn.com/smourier/archive/2004/07/13/181836.aspx

This is a great post from Bryant pointing towards some essential information on writing secure Web Parts.

http://blogs.sqlxml.org/bryantlikes/archive/2004/06/30/753.aspx

http://www.bluedoglimited.com/Downloads/pages/Web%20Part%20Toolkit.aspx

Contains:
InstallAssemblies
SharePoint Configuration Analyzer
SharePoint Explorer
Inspector Web Part
GhostHunter Web Part

http://www.sharepointblogs.com/spdiary/articles/ToolPaneCustomization2.aspx

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odc_SP2003_ta/html/ODC_SPPTBuildingCustomChannelsSPPT.asp

Thanks to Patrick Tisseghem for this.

Yes, using this code:

http://www.reflectionit.nl/WebPart1.aspx

What might suit better is Jan Tielen's SmartPart as it lets you call the SharePoint OM from the controls:

http://weblogs.asp.net/jan/archive/2004/06/10/152932.aspx

You need to include your programmatically created site in the Site Directory list! (from MSD2D)

//Get reference to the portal
SPSite myPortal = new SPSite("http://localhost);
SPWeb myWeb=portal_site.AllWebs["SiteDirectory' target='_new'>;
SPListCollection myWeblists=myWeb.Lists;

//Get reference to the site directory
SPList siteDir= myWeblists["Sites' target='_new'>;

//Add an new entry
SPListItemCollection listItems = siteDir.Items;
SPListItem item = listItems.Add();

//Assign values to the list columns
item["Title' target='_new'> = objCommunity.Name;
item["Description' target='_new'> = objCommunity.Purpose;

//update the new list item
item.Update();

Nigel.