Please don't spawn popup-windows like this:
<a href="javascript:window.open('foo.html');">

or this:
<a href="#" onclick="window.open('foo.html');">

rather, use:
<a href="foo.html" onclick="window.open(this.href);return false;">

benefits:
- statusbar still indicates where you're going
- non-js users (and search-engines) still end up at the correct page
- current page doesn't jump to top (faux-anchor '#' evil)
- shift- and right-click options still open the correct page

Update:
Apparently using return false; in the href can mess up some browser's popup-blocking, so watch out if you care about that (haven't noticed it myself, but then again, I almost never use popups). [via]