CAB and SCSF resources
I've been extensively using the CAB (Composite UI Application Block) and the SCSF (Smart Client Software Factory) lately. You should really dig them if you are creating Windows Forms applications. The CAB is a great tool to structure your developments and create reusable components. The SCSF is great for working with the CAB...
Eugenio Pace, product manager at Microsoft Patterns & Practices, has compiled a list of resources about the CAB and the SCSF. This can be really useful if you are using these technologies or want to know more.