Sorry to drag this up, but it is an issue with me as well.
Don't get me wrong, I understand the need to place ads on the free accounts and have them always visible. I am also very grateful for your free service. Nowhere else have I found a setup such as this.
It'd just be nice if the code were valid.
I personally think that it should be made to be for sure valid with XHTML 1.0 strict (as that would work for everything previous as well), but even a simple HTML 4.01 Transitional or Strict would be nice.
It isn't that hard to change the code to make it valid. How you get it to insert to the correct place (ie - inside the <html> and <body> tags so it doesn't throw an error)... I don't know if that is as easy, because I don't know how you get the server to insert the code onto each page.
You could probably ask many people on here and they would be glad to take your code, change it to make it valid, and give it back to you.
Furthermore, as I think people have pointed out on other posts (I only did a cursory search), the ads disappear when a page is sent with the application/xhtml+xml MIME type and viewed in a browser such as Firefox or Opera. I don't believe there is anything wrong with this (on the part of the user) because the PHP code to make the page send as xhtml+xml isn't meant for removing the ads but to correctly send XHTML as it is meant be sent. Also, if the code for the ads was simply updated they would not disappear.
Granted, the ads still appear when viewed in Internet Explorer, so a large chunk of the Internet audience still sees the ads; however, if you want your ads to be more effective, you should update the ad code and make sure it will display for people using Firefox, Opera, or other standards-compliant browsers.
I don't really consider this an issue of "appease the free users," but more an issue of making your hosted sites more compatible for everyone, and making sure your banners always show up on the free user pages.
Looking forward to any comments/thoughts/responses, whether from other members or from 100webspace support people...