Please read this comment before deciding whether to download. (Zotlan)
This just checks all a elements (links) and removes target attribute, so they will not open in new tab. target=_blank is extensively used on the Web, but it is very annoying. If user (especially advanced one) want to open something in new tab he/she will do so manually (i.e. using middle click of moue), so this script make life easier and removes all automatic opening in new tabs.