Want to know how your Web site looks to the search engines?! You should. BrowserShots is a fabulous tool that works beautifully.
How about a host of tools that will be compatible with any browser? They're called Perl Scripts. You can have a guestbook that blocks profanity and spam and IP addresses, or allow people to search your Web site, or have quizzes and more, so long as your webhost supports scripts.
View your Web site as other people do with SiteViewer. You might find out that your Web site is not compatible with every browser and your site doesn't look quite as seamless as you think it does.
Use this LinkChecker to make sure that you don't have any defunct, useless links on your site. It looks so unprofessional when you click on a link and you get a dead end.