Few more research

There were so many wonderful sites where I could strongly feel the theme of a 'space' whether it was their true theme or not. These are some of those:

http://www.redwebsite.com/
-simple and clear. but using perspective makes a 'space' within the site.
generally, it is used as a layout of the site. main menus. images appears in the image frame.
it shows that 2D image also can achieve the 'space'.

http://www.lisent.net/
-interesting and fun. full flash site as well. By using 2D photo of paper box, it effectively express small space. Image of two men also makes box as a 'space'. In each menu, those guys do different activities with different elements of interior. there are some little animations such as moving clocks, swinging airplane toy, moving bugs, etc. These little elements makes whole site more interesting and gives a life on these two man and the space in the box.