In Firefox, if you have the Web Developer plugin installed you can view the cookies a particular site has setup in the browser.
Is there a way/plugin to do that in another of the other browsers?
CookieSpy is a free tool to view IE, Firefox, Chrome, Safari and Opera cookies.
In Opera it is built-in, and you have two choices. The first is to use the super-useful site preferences dialog (found in the context menu):
The second is to use the cookie manager (Tools > Advanced > Cookies...), which lists every site and every cookie; you can quick search through it easily too.
And with either method, every cookie value is editable, so you can easily hack your cookies:
Cookie Viewer - this Power Tool automatically scans your computer, looking for "cookies" created by Microsoft's Internet Explorer, Netscape's Navigator and Mozilla Project's FireFox web browsers.
Free for non-commercial use only.