Glims allegedly does this, I couldn't get it to work months ago and haven't tried again since. I just got used it since I only began to see it with IE8 anyway.
Glims will give you something like what Firefox uses, namely that you go to the search bar and then can pre-select the engine (just about anything that you can think of), this is what my roommate uses.
I prefer to use Inquisitor, which has an advantage in that I can open a new tab (CMD+Tab), go to the search bar (Tab), type in my search term (delicious beer) and then hit a user-defined keystroke (CMD+Shift+A) to buy some 'delicious beer' from Amazon.
If I understand what you are wanting correctly... you want to have google.com set as your new tab page. You also want it set such that when you open a new tab it leaves the address bar selected and not the google.com search box. I think that Safari 5 does this (or for all I know it is a setting in Glims).
Glims
So, long story short, get Glims at the minimum (this will also put favicons on your tabs, something that I like), and also get Inquisitor if searching with a keystroke appeals to you, especially since you can jump from site to site with the same search term. Like, say I search for 'Mighty Ducks', and hit CMD+Shift+N to go to Netflix to see if they have it on instant play. Oh look, they do, but you know what, I want to own it too... So I hit CMD+Shift+A to check the price on Amazon, and if that is too expensive, CMD+Shift+E to get it cheaper on Ebay.
It is nice to have so I don't have to open new tabs unless I want to.
Also, Glims will give you website previews on Google and Yahoo.