Building asp.net apps for multiple customers

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Hi,

I am sure this has been discussed before but I can't find much on it. I am
building a hosted asp.net 2.0 application that is going to be used by
mulitple customers. Or course they should only be able to see their own data
and there is a possibility that they may want to customise their own web app.

So what is the standard for doing this? Seperate websites on IIS for each
customer? Seperate databases for each customer or a shared database?

Thanks