A few bookmarklets in your browser
window.resizeTo we can create bookmarklets. They are just lika ordinary bookmarks, but in stead of taking you to a new page or site they can manipulate the content of your browser. Such as the window size:
Drag these to your bookmarks bar: Fill 1024 800
You will need a modern browser, FireFox and Safari will work this trick like a charm (Opera, however does not accept these scripts). In your browser of choice create a new bookmark, rename it to e.g. Test for 1024x768 screens and for the content of the bookmark, paste this code into that field:
A bonus for Safari users: If you put these bookmarklets in your bookmarks bar and press ⌘+n where n is the order in which the bookmark lies in counted from left to right. On the image above, invoking the 800 bookmarklet would be done with ⌘+3.