Well, your site worked in almost every browser I tested it in - Firefox 2, Firefox 3 RC 1, Lynx, Maxthon 2, Safari 3 for Windows Beta, Slepnir 2.7, Internet Explorer 7, Netscape 9, and Opera 9 - however, it did hit glitches in Internet Explorer 6, and in Internet Explorer Beta 8.
In the case of IE 6, your search box gets a bit out of whack (the "check" button moves to below the box, and the green box around it gets cut up a bit), and your logo has a grey background. However, considering IE 6's clunky handling of CSS and transparent PNGs, it doesn't look too bad, and it is still completely usable.
In EI 8 beta, everything looks great with one exception - the "FAQ" link/tab jumps down slightly, so it's about half in the white area, and half out of it. The Home link still looks fine, however, and so does the rest of the page.
Other than in those two browsers, though, I didn't hit any problems (and personally, I'd only worry about the IE 8 one).
Design-wise, I like your site. I can't say I love it, as it's got a sort of generic "web 2.0 look" and doesn't really stand out from a lot of similarly designed sites, but it's not at all unpleasant either.
I do like your choice of colours and the amount of white-space in your design. It's very clean and easy on the eyes. I also like your ad placement and the style of ads you used - I found them noticeable, yet unobtrusive.
Feature-wise, your site worked as expected and gave me the information I wanted to know. I can't honestly say it stood out too much, as a lot of other sites are offering the same functionality as yours - however, yours is much better looking and less cluttered than many similar sites, which I liked a lot. I also found the "Last Checked" area at the bottom kinda nifty. The "FAQ" could also be a stand-out, depending on how detailed you get with it when it is finished.
To sum it up - pretty much everything works, and your code is all valid, which is great. Your design is clean and easy to read, and your tools work as they should. Overall, it's a solid site. Once your FAQ is finished, and you've implemented the "under construction" features listed on your main page, I could definitely see myself coming back to it in the future. Great work!
-Patrick J. B. Simmons | @hobbramble
"If I could give you one piece of advice to remember for the rest of your life, it would be this: when Patrick tells you to do something, do the opposite." - Nolan Ladewski