I honestly hate that the default function in Firefox is to open a tab from a link right next to my current tab. I suppose others have their idiosynchratic preferences, but this one is mine!
To fix it, in both Firefox 3 or Firefox 4, type ‘about:config‘.
Next, search for ‘browser.tabs.insertRelatedAfterCurrent‘, set the value to ‘false’ as shown below.
This tip is brought to you by the number 4 and the letter F.
Cheers,
Herlo

That bugs me too and I had no idea you could change it. Thanks for the tip!
Anytime, John.
I can’t seem to get this setting to STAY THE WAY I SET IT. I change it, then a couple of restarts later, it’s back to false. Very maddening.
Any way to lock the setting so Firefox doesn’t change it again later?
Odd, it stays for me. I really don’t have any other suggestions, off hand.