SPContext.Current does not exist in Workflows

Maybe this is obvious, but I just learned it the hard way: SPContext.Current does not exist in Workflows.

So when you have an external Assembly that provides some functions, make sure to pass a SPWeb into those functions, as SPContext.Current is null and you don't have a SPWeb or SPSite.

On a similar Note, SPWeb.CurrentUser is the system account usually, so if you need the User that started the workflow, pass workflowProperties.Originator into the functions as well.