Win32 API

Accessing the WinAPI
Provides a basic, step-by-step guide for using and understanding API.
http://www.devarticles.com/c/a/Visual-Basic/Accessing-the-Windows-API-in-Visual-Basic/

Dutch's Software
Code samples and examples of advanced API through subclassing and shell API.
http://www.dutchthewiz.com/vb/api/

Ex-designz Win32 API Reference Library
Categorized reference library of many different API functions with examples.
http://www.ex-designz.net/api.asp

Microsoft Windows API Reference
Microsoft's knowledge base.
http://msdn2.microsoft.com/en-us/library/aa383750.aspx

Morty's VB Workshop
Sample code and tips as well as an API library with function examples
http://www.geocities.com/SiliconValley/Ridge/1057/

TheScarms Visual Basic Code Library
Examples showing how to use Win32 APIs.
http://www.thescarms.com/vbasic/

VB Programmers Guide to Win32 Api
Book by Daniel Appleman.
http://www.desaware.com/VBPGWin32APIL2.htm

VB Vision
Win32 code samples, tips, tricks for the VB developer.
http://www.mvps.org/vbvision/

vbAccelerater
Devoted to providing advanced tips and techniques, covering the Win32 API, graphics, DirectX and ActiveX programming.
http://www.vbaccelerator.com/home/

VBForums
Forum for WinAPI relate topics in Visual Basic. Ask or answer questions posted by members. Membership required to post.
http://www.vbforums.com/forumdisplay.php?s=&forumid=8

VBnet Developers Resource Centre
Win32 API code for Visual Basic developers. Reference, code samples, FAQ.
http://vbnet.mvps.org/