Simple question, spurred on by the removal of the target attribute in HTML 4.0 Strict and XHTML 1.0 Strict.
I personally don't think so, as web users become more savvy, they'll ask for a new window from the browser. It annoys me when a website does this a lot.
I think the question is sort of subjective. It could be good if you're launching a javascript game or something.
On social content sites like Digg or reddit I prefer links to be opened in a new window/tab, as I am constantly going back to the original page to grab more links to look at.
That being said, I think that wherever you can you should allow a logged-in user to make the decision for themselves. I know Digg allows users to choose how they want links to behave.
I think this is pretty subjective, so I'll just give my opinion as a user. I prefer if it's just the default behavior. If I want it in a new tab, I'll middle-click.
If you're going to open it in a new window, warn me like this [new window] or something.
I do if it is an external link, other than that it is probably a bad idea.
As a law, there is an exception to every law. Although in most cases simple links are best, sometimes links in a new window are just what is needed.
For example, I very much enjoy blogs and forums that open any external links in a new window, so I don't loose track of the original post I was reading.
Another good place to put them is when you click on a picture to get a larger version in an internet store or something.
You really have to evaluate this on a case-by-case basis, but my opinon is that in the end both are necessary for a good UI.
Yes, in web apps it sometimes makes sense to use a popup window when pulling up something ancillary that you need to look at without losing the content on the page.
For instance, I have used popups to display reports. In those cases (which are situational), users needed to look at the report and the screen at the same time, not navigate away to a reporting interface.
The only time I force a new window is when the page I'm designing is ment to be used as a Web Part for a Sharepoint site.
I look at it this way, if you force a new window, you have taken choice away from the user. That's bad.
With two exceptions, the answer must be a resounding "no".
Rationale: Yes, as others have already pointed out there are many cases where I prefer to have a link opened in another tab. But thanks, I'll make the determination of when and which myself. The basic tenet of the web is that the user is sitting with a user agent, a.k.a. web browser. The browser is in other words an agent on behalf of the user. If I'll want a particular link opened in another tab, I'll command-click (or ctrl-clik on another OS), and if I don't, then I'll click regularly. When a link on a web page opens the link in a new tab without my asking, it annoys me no end and breaks the predictability and familiarity of the web.
Exception 1: When clicking to see a large version of a picture or some other plain pop-up window. I see this as a separate topic.
Exception 2: Fully Ajaxy web applications, which seem to set aside most of the rules of the web anyway.