Expression Blend, believe or not, has an add-in model. It’s highly unsupported but it exists. The unsupported nature of it means that you have to do a little Red Green style patching to get them to run in the first place and if they cause instability, don’t call Microsoft support. However, there are a couple of really cool ones that are out there.

To read all about these add-ins and how to get them running in Blend regardless of where you launch it from – check out my post at Three Essential Expression Blend Add-ins