[inafield]

I completely agree. Why should the admins limit the functionality when there is an existing usage that is perfectly suited for this?

The scroll wheel in my mouse can be used as a middle click to open a new tab. On some laptops with trackpads there are even gestures for middle click even if there are no buttons.

[dohertyjf]

So keep internal links (to discussions, etc) as default and external links as _blank.

Problem solved.

[wam]

No, problem exacerbated. You have 3 camps of people here. One camp expects to only open new tabs when they choose to. Another wants (and sometimes expects) links to open new tabs always. The third camp prefers to open new tabs for "external" links and not for "internal" links, and would like to see this behavior become a convention (expectation) as well.

Leaving aside the problem of what counts as an "external" link (is a link from Gawker to Deadspin "external"? Depends on how the user perceives the relationship between those sites), you're still just muddying up the web's UI conventions. That's what "default" link behavior is: a UI convention.

Not knowing where a page is going to open on the screen is a huge problem for users. Requiring them to learn why one kind of link replaces the content in the tab they're currently looking at and another kind of link opens in a new tab only makes it harder for them to "engage" with the websites they're trying to use.