I found this tip via Macworld a while ago, but it was meant for use in Safari. However, in making my switch to Firefox, this was a feature that made the jump all the more interesting because it works in this browser as well. Here’s how it breaks down from Macworld.
Launch Safari (or your favorite browser) and create a new bookmark. Most browsers will require that you bookmark a specific site. In Safari, open a site and then choose Bookmarks: Add Bookmark. Give the bookmark a name that will help you remember the screen size, such as 800×600 or 1024×768. Next, edit the address of the bookmark—in Safari, go to Bookmarks: Show All Bookmarks and navigate to your newly created bookmark. Change the Address portion of the bookmark to:
javascript:self .moveTo(0,0);self.resizeTo(800,600);Open any page in Safari and select the bookmark. You’ll see that page in an 800-by-600-pixel browser window. You can then duplicate this bookmark and create other sizes as needed; just change the name and the relevant code. When you’re done, move your new bookmarks to a convenient location; then click on them when you want to test your pages at different resolutions. [macworld]
I like to have three of these bookmarks in my toolbar. From small, medium, to large, it gets very useful. I’ve even gone as far as making them slightly button-like, naming them “-“, “+”, and “++”. You can minimize and maximize windows all you want, but to make it quick and simple, just hit your bookmark and you’re done.
This might not be too handy for those folks out there that don’t have a lot of real estate on their monitor. If you run a monitor at the screen size of 1024-by-768, then you might not see the advantage. I can’t be sure if this works in the world of PC’s, but it stands to reason that it should. It’s great for previewing how websites you are working on look, but I just like it for the simple reason of keeping everything on my screen in a more controlled state of chaos.