Am looking for professional PHP scripts to design some websites that can deliver professional quality services, Where i can get most useful PHP Scripts on internet.

Please advice..

Do you mean you're looking for Content Management Systems? Or varied scripts to provide various functionality?

In which domain you wanna develope a site?

SourceForge contains a large collection of scripts.

There are lot of php script softwares available in www.iscripts.com for website development.

I found some very useful PHP tutorials at www.devshed.com/c/b/PHP/

try http://gscripts.net/ and http://sourceforge.net/

Also try: HotScripts

-Alex