I didn’t realize how much I wanted this feature until I found out I could do it. Instructions below.
If you choose to use this feature, each time you open up Firefox or hit the home button it will load multiple homepages. One of them in the foreground and one in the background. To do this just go Tools - Options - Location(s). In this field enter as many URLs as you wish separated by a space and a "|" in between. (EX: http://google.com | http://yahoo.com | so on...). This is a great feature if you have multiple homepages that you like to visit often. Also remember that choosing too many pages at once will cause the Firefox to take much longer to start up.
Go to Tools – Internet Options – General Tab. For specifying the home page tabs explicitly, type the URLs of all the websites, each in a new line in the ‘Home Page’ text box and click OK. The next time you start Internet Explorer, all the specified websites will be opened in a single window in multiple tabs.
CLICK the little Wrench and go down to "Options" and in that first tab it says "on startup" the third bullet is "open the following pages on startup" then just add what u want.....ya dig?
UPDATE: Despite that I love this feature upon browser startup, occasionally I like to open a new tab while already browsing and hit the Home button (www.google.com) …but now 4 new tabs open up every time that I don’t want. I guess I could mitigate this by just using the Google search engine in IE instead of going to the website.
UPDATE #2: In Internet Explorer, whatever homepage you have listed first in your list, well when you open a new tab it will default to just open that one...thereby circumventing having to hit the Home button which causes the unwanted occurrence of opening up additional tabs that you don't want opened.
UPDATE #3: Actually I'm realizing I don't really like using this feature much, at least not more than two homepages. Any more than that causes the browser to open up super slow the first time.