Mostly how to get VBA, VB, and VB.Net to call a DLL written in C... and more problematically, how to pass numeric arrays to & from same...
- Writing C DLLs for use with VB (Sandsprite.com)
- Reusing Legacy DLLs in C# (TheCodeProject.com) - helpful for VB as well
- VB.NET & callbacks from C - a minor odyssey - a description of getting a 'legacy' optimizer written in C to work with VB.Net
Related - calling the Win API involves many of the same issues
- Using the Win32 API in VB (AllAPI.net)
- Fine-Tuning Control over API Functions with DllImport (CodeNotes.com)
- Visual Basic Secrets - how to get at goodies lurking in the Win32 API
Miscellanous along the way...