On my website there is a guestbook which opens another browser window. Many of the visitors to our website are having issues opening the guestbook in order to post. What do I need to do so that these guests can post to our guestbook without disabling their pop-up blockers?
Why don't you just let it open in the same window?
Alternatively, I've never seen any problems with this :
<a href="http://bonrouge.com" onclick="return !window.open(this.href);">bonrouge</a>
Aside from that, basically nothing.
There are a plethora of different pop-up blockers out there, and each one has its own set of criteria for deciding which windows to block. The only way to safely work in all of them is to open your guestbook in the same window. (Though most blockers seem to not have a problem with windows that are opened as the result of an html link with a target="_blank", but that's no guarantee).