In reply to alibaba:
'Open in new tab' is probably better 'netiquette' when linking to an external site, since it doesn't muck up/lose the page you're currently on. You either have to 'close tab' for the newly-opened link when you're done with it, or go 'back'. Both of which are single operations. If you do a lot of navigation on the linked site, not opening a new tab means you have to do a lot of 'back' clicking to get back to where you linked from. Opening a new tab means you just close the new tab when you're done with the new site, and switch back to the calling page.
The behaviour for tab navigation can be changed with browser options.
I prefer it to open in a new tab, because that's what I'd do anyway; it's how I read threads. If the thread list pages opened threads in a new tab, rather than following the link and replacing the content of the current tab with the linked page, I'd be a happier bunny.