Wisconsin photo by James Jordan
I recently came across Gigasoft Development, a small firm that specializes in writing IE and Outlook plugins. This is the first group I've come across that is solely focused on these, and whilst I've never used them myself, their work seems impressive.
If there's any part of your software development you'd want to contract out, it's writing extensions for Microsoft products. I know from my own explorations that it's an incredibly deep field, with undocumented gotchas everywhere you turn. It's a waste to devote months of your own engineering schedule relearning all those lessons if it's not part of your core technology. It's pretty rare to have good web developers who can also handle the hard-core Win32 hacking too. Contracting out to a good team of people who already know where the booby-traps are means much quicker and cheaper development.
You can often follow a pattern where the plugin itself is just a thin shim that fetches and renders HTML from a URL you control. That gives you the flexibility and ease of web development for the UI aspects, and means you can update the application logic without touching all those installed plugins.
I also have a soft spot for Gigasoft after looking through their site and spotting that Tom's a Packers fan from Wisconsin, and they're based in Illinois. I always love visiting Chicago and Wisconsin when we fly back to see Liz's family.