i hav got a project of web development using php..
i need to hav an idea for a good website.. ( a dynamic one)
Well your looking at one right now...
I don't know if you will find many sites that will give you their php source code but you can look at tutorials to find out how to do specific things and get a general idea of what method certain sites are using by being observant.
Daniweb does some fancy thing and rewrites the URL before processing it so it does a lot of stuff that you can't see so look elsewhere for that. Be observant of things like "?var=value" on the end of URL's (that's using the GET method of transferring data) and when your being redirected and you might be able to get an idea of what they're doing.
For actual html, you can look at sites like www.lyricwiki.org, www.youtube.com, www.westpac.com.au, www.escapistmagazine.com and www.newgrounds.com and check out their source code, the style sheets they link to etc. to see what methods they use to layout their page (mostly <div>'s and never tables).
There are also some addons for Firefox (I think) that let you have a look at how the page is set up which can be very handy. I think it was called firebug in FF 2.