Well first they have to be done in CSS. Tables can only be used for tabular data. Second they just have to look good to me. Beauty is in the eye of the beholder so I do not expect every site that is posted to be liked by everyone or even anyone. Also do not expect a site to be posted just because you sent it in.

With the large amount of submissions I get daily and the increasing number of showcase sites, getting your site into the Vault will now be more challenging. I look for use of color, typography, whitespace, IA and how they all fit overall in the site’s structure.
Can I submit any site that I think is good?

Sure you can. It just doesn’t have to be your site, it can be any site on the web that you think is useful. If you submit a link and it gets put up on the Vault, I will make sure to give you “props” in the entry.
Do the sites have to validate?

Most of these are commercial sites so I will leave it up to you to answer that question…
Comment Guidelines

Generic “this is nice” or “this is crap” will be deemed unuseful to the discussion and deleted. I am not setting up a communist site, but one that allows for quality discussion on the design merits of the site. If their is something about the design you do not like, feel free to express your opinion, but please provide justification so that everyone may benefit. Same thing goes for if you have something nice to say.
Featured Site

For now this is just a top quality site from the previous month.
Recently Redesigned

A site that has been recently redesigned and the redesign deserves to be notice in the vault. Not all redesigns improve upon the previous design and some may even justify removal from the Vault (won’t happen) so not every redesigned gets noticed.

An award winning school management software based on ruby on rails. It is highly powerful and highly customizable
Very good use of shades of red. And a neat web 2.0 look with focus on usability and rich user experience.