If you haven't had a chance yet to see these great videos that Kathleen has made of VSTO in action, check them out. They're each about 6 minutes long are are really nice glimpses into some of the cool features of VSTO 2005. Keep 'em coming Kathleen!
Demo 1 – Locate and Delete NamedRange Controls
Demo 2 - Resize Controls Within Worksheet Cells
Demo 3 - Add a Custom User Control to your Document
Demo 4 - How Column and Row Order is Persisted in a Data-bound List Object