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 ‘ï»¿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.