newTabPosition v0.1
If you are in the middle of a bunch of tabs and decide to open a new tab to do a quick search and then close that tab, chances are you will be dropped at the end of the tab bar and you won't know the last tab you were looking at.
This extension will set the browser.browserSettings.newTabPosition setting to "afterCurrent" so that new tabs always open next to the currently active tab.
This extension is similar to the "Always Right" extension (which I didn't know existed because it didn't have the newTabPosition search term) but my extension requires fewer permissions.