This stack is a result of a request posted here: http://www.realmacsoftware.com/forums/index.php/forums/viewthread/33023/
I will include a instructional pdf for it later today but wanted to go ahead post this up. I'm not sure if I did the .dmg file and it's contents correctly as it was my first attempt with this as well.... so if there's an issue with this I'll have to correct it later today as well.This stack includes a snippet for the image source html so that if you desire to link an image instead of text you can. Simply place that html in place of the text in the "Link Name" area, and then drop in the url of your image.
This stack allows you to customize the popup message, however in my testing I found that if your message is to many characters that the popup won't occur. So keep your message short, sweet, and to the point. You can also easily define the link path (url), and you can even choose if you want the link to open in the current browser tab/window or in a new one by clicking on the "Open in New Window" box. This stack is simple html, so further customization is not possible but you won't have to worry about it conflicting with other stacks though.... I have a demo page setup with this stack placed in Joe Workman's Lightbox stack: External Link Warning Demo
Here ya go, enjoy, and it's free: http://www.rapidlywoven.com/free_stacks/external_link_warning_v1.dmg
Updated with v2.0 (refer to post 12 in this thread for further details): http://www.rapidlywoven.com/free_stacks/external_link_warning_v2.dmg
I've got a few other simple stacks I will be tinkering with soon and hopefully should have more FREE stacks for the masses to use. :D