Ok, so I had an idea to change from a day theme to night theme layout according to the viewers timezone. I was wondering if this was possible to embed into flash, or easier using javascript...or some other form of coding. I also have no idea how to do this, im going to begin researching it right now, however if you have any coding/info that would help, it would be appreciated

http://alistapart.com/stories/alternate/

instead of the onClick event to choose, check the time and call the setActiveStyleSheet('morning | afternoon | evening | night')

A server side code would be better than checking in javascript all the time on client side. That's my opinion anyway.

It would, providing that all your site visitors were in the same time zone as the server.

No, not really. PHP or ASP can read a cookie as easy as Javascript can and it's server side and will always work even if javascript is disabled

What do cookies have to do with it? Can you use PHP to set a cookie with the difference between the users timezone and the servers? As I understand it the only way to determine a users timezone is to either ask them or to figure the offset between what JS says is the users timezone and your servers timezone.

Well chances are if you have users, with profiles (making an assumption) all you have to do is ask them in their profile, other wise they'd get server time. That's what message boards do and I think most CMS that have that type of application ask them. It's not an uncommon practice.

I would have thought that

Ok, so I had an idea to change from a day theme to night theme layout according to the viewers timezone.

would explain that the OP doesn't want to use server time.

And you shouldn't assume anything about some one elses intentions.