Importing module with name given as a variable

[Sean Davis]

What is the "best practice" for importing an arbitrary module given
that the name is stored in a variable?  The context is a simple web
application with URL dispatching to a module and function.  I know of
__import__(), the imp module, and exec.  For each of these, is there a
way to make them work "just like" the normal import call?

Thanks,
Sean