While designing my site I am constantly faced with the issue of whether its ok to TAKE ideas and designs from other sites. In some cases there is no distinction in certain aspec
Depends on how much you 'steal'.
Code
If you're ripping off the whole design, then its a bit dodgy. If you like (for example) the Stack Overflow concept of voting up stuff, then steal the concept and use it in a different manner. If you want to know how say the orange highlighting of the up-voted items works, then look at the code. But don't do both and steal both the concept and the design, you'll just create a clone.
Due to the way different web browsers treat CSS and the like, there are often only a very few limited ways to do a particular thing (3-column layouts, etc.). It seems fair enough to blatantly copy in these cases where there is a common way of doing things. Where its something unique, and there's many ways of doing it, it seems a bit more off to blatantly copy.
Graphics
Ripping off graphics - not so okay. Images have been around a lot longer than code so copyright law, etc. probably suits them better. If nothing else you have to contend with possible watermarks or other metadata to identify the original source. It's very easy to check for image stealing, less so for code within a larger block.
I'm a coder, not a designer so what I tend to do is borrow graphics that I like just while mocking up my web-app for internal use. Does that seem fair? I'll change them for newly-designed or paid-for ones before going live. At least that's the idea, though it could be far too easy to forget and use them by accident.
That's the way it works in the newspaper world (well it used to, not sure now with the advent of this there Internet thang): You download as many graphics as you can bother waiting to come over your 57.6k modem; you only pay for the ones you actually publish.