My homepage (which is what the thread asked for) on most of my browsers, is Google - http://www.google.co.uk/
I use Seamonkey almost all of the time, so I get full control over....
On navigator start up, I display a blank page.
On opening a new window, I display my home page.
On adding a new tab, I display a blank page.
(I rarely open more than the single navigator window, but it's handy to be able to go straight to Google with one, when I know I am about to (probably) click a whole load of links, as tabs. That game works nicely in a distinct window, which I can get get rid of, in one fell swoop, when I'm done with it.)
Where I get the option, in other (lesser) browsers, I do roughly as above.
I.e. in Firefox, I seem only to have the option of setting what to do "When Firefox starts:", which seems to apply both then and when I open an additional window, so I set that to a blank page. There seems to be no control over what a new tab starts with - it is always blank.
Opera I use rarely, and at a glance, it seems as restricted as Firefox.
Konqueror is a little better.
Begrudgingly, I'll admit IE7 gives some control. 
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"Striking up conversations with strangers is an autistic person's version of extreme sports."
Kamran Nazeer