Looks ace!

I can second Unity3D. It is very good quality and has some A* shaders. It plays ball with lots of browsers and best of all the normal version of it is free to use.

Here's some stills from an architectural walkthrough program that we're creating with Unity called realis3d. It's a bit different from what you want but it shows you some of the results that are achievable in a normal web browser.

PM me if you want help getting started!

Hi everyone,
Just to let you know that a new more stable version of REALIS3D is available at http://www.realis3d.com
Look forward to hearing your feedback...
RV Team

Hey everyone,
So we are still looking at price point but there will be a free version. The Pro version, which is with everything, no further costs for scenery, objects etc... will be no more than £800. This also comes with free cloud storage, collaboration, web hosting for html published scenes and cloud rendering.

In regards to the interface, there is a lot of work to do and we know that. When you press and hold space, you get the hotbox. If you hover over an icon and release, it will action the request. If you press escape, it will load up the other menu.

Finally, I would suggest having a look at the youtube and website content http://www.realis3d.com for better instructions.
Thanks for looking

Real Visual

Hey everyone, so we created an account on here just to say and thanks for starting the thread. We wanted to engage with sketchup users here. Have had lots of positive feedback so far, thank you.

Please let us know how you get on and as soon as we get import of sketchup FBX working, we will let you know!
Thanks,
Real Visual Dev Team