I’ll tell you when I do stuff that’s cool, and when I do stuff that doesn’t quite work at all. Looks like I’m stuck on another issue with .NET. I’ll have to do something cool just to make up for all the bad news lately. 
This is a good question posed in an MV forum. I think this question and answer are good for a more general audience so I’m responding here.
It’s time to call it quits for now. Yup, I give up. I’ve killed an entire week on this, well over 100 hours. I have clients that need attention and this project isn’t earning its keep. The code is working great on development systems but I can’t get it to work properly on a non-development workstation. I’m am closing this for now with a definitive current tutorial which works to some extent - it doesn’t work entirely but the data is much more accurate than old blog and forum entries you’ll find out there. Maybe someone from Microsoft can correct the errors - or look at my systems with me so that we can make this work and document it for everyone!
Andrew Whitechapel’s generous bloggings on Automation Add-ins and shims are chock full of helpful information. Unfortunately the blog entries are also over two years old and I’ve just found out the code details are no longer valid.
The task is to create an Excel User Defined Function with managed .NET code. It seems so far that the way to go is with shims which proxy COM requests from Excel and separate the managed code into its own application domain for security and stability. This short article summarizes how I’ve come to that conclusion.
I’m continuing my notes here for anyone else who needs to tread through this minefield. At the moment my code is working great on systems that have Visual Studio installed, but not on another test system without VS. Sigh. That means I can’t deploy this code yet. See the Summary in this article for the current status, and see the first article for more links and details.
If you’ve been reading my other blog entries, you know I’ve been working a lot with Excel lately. I worked intensely with this environment several years ago. I’ve found all of the Microsoft Office applications to be fun to work with at the object model level - OK, call me a geek. Unfortunately MS Office apps have always been far behind the technology curve when it comes to developer tools. These are my notes about how to do the development that I need given the state of the tools available.
A long time ago there was a product called CrowFlight that retrieved data into Excel from MV. Some companies still have it and I occassionally get a call from someone looking to replace it. Well… I now have two ways of using Excel formulas to call into MV, and this functionality can be combined with NebulaXLite.
We released a new product today, though it’s been on the website for about a month to start drumming up interest - and that it did. NebulaXLite allows MV BASIC to create "real" Excel workbooks - and it seems to work with OpenOffice and Google Doc Spreadsheets too! We also have a new forum to discuss our product and service offerings.