Edit to clarify Thank you for the existing answers. I am afraid that you misunderstood my question. I don't want to create mockups (I have some, but they are not suited for my current purpose). I want a tool (possibly something as simple as a freely available CSS theme) which will make my existing, functioning half-finished ASP MVC site look like a mockup.
My boss's boss decided that I have to show the current stage of my work to my stakeholders, so they can get a feeling for the web application I am developing for them. It is a greenfield development, so the users have no expectations built from contact with prior version. He wants it to be at least a little bit clickable, so I can't go and post the mockups I am working from. It will have to be a running version of the current stage of development.
I want to make it crystal clear for the busy, critical mid-level manager that what they see is not what they are going to get, but an early sketch of it. It is a very sensitive matter, because my application increases the manager's paperwork load. Therefore they are already hostile towards the project and inclined to view the prototype in the worst possible way, making conclusions for the expected application quality from the design quality, and complaining that the vital functions whose implementations has not yet started are missing.
To do this, I would like to give my page a hand-drawn look, just like typical mockups. It should shout "I am a rough sketch" from afar, so that nobody could ever mistake it for the real thing.
What are good ways to create such a look? Is there a way more efficient than creating my own mockup-look CSS by hand? I am severely limited in the time I can invest in such a task, and I am also inexperienced at design. I need don't a perfect look, and the pages are nothing complicated, so the simpler the solution, the better.