I have suggested a stack exchange for Excel Q+A's. I've asked several about VBA and Excel and they often tend to go down like a lead balloon on the stack exchanges I would ask (Stack Overflow and Superuser - SuperUser in particular seems to have a hard core of people who really strongly dislike Excel q's.
I've put it under tech but it could equally go into Business.
EDIT - in response to "SuperUser" being the place for it, Super User itself says its regarding the following: -
What topics can I ask about here? Super User is for computer enthusiasts and power users. If you have a question about … •computer hardware, •computer software, or •personal and home computer networking and it is not about … •programming and software development, •video games or consoles, •websites or web services like Facebook, Twitter, and WordPress, •electronic devices, media players, cell phones or smart phones, except insofar as they interface with your computer, •issues specific to corporate IT support and networks, •asking for a product, service or learning material recommendation,
They may not be off topic, but the excel questions often simply do not get answered on SuperUser. Largely, Superuser seems to be far more about the nitty gritty of computer hardware, software clashes and issues and networking. Questions about excel are often ignored.
After being directed to the metathread on Superuser I was previously unaware of I had not noted that SuperUser itself is moderating this issue and resolving it.
I'd still like to see a Microsoft Office SE, but I guess we'll just have to try and get that one off the ground. I am kind of the Excel "Guru" in the office here and I'm aware just how complex Excel can seem to the casual user, and how complex even PowerPoint and Word can get to power-users.
Edit: As a reply on your comment about SuperUser not always answering the questions about Excel, there is a meta thread which actually goes against that: Microsoft Excel questions are very common here on Super User and are clearly on topic as computer software questions, so please don't vote to close as off-topic.