Target Equals Underscore Blank
You know what I grouch about with surprising zeal? Links that pop up in a new window.
You know what really tweaks me about it? Clients, IA's, and designers who favor such links because "we don't want the user to leave the site".
Hurr... then don't include hyperlinks in your page--they, by definition, allow a user to navigate from (ie. leave) one site to another. Better yet, stay off the web and stick to making glossy brochures or PDFs.