I personally would like a few of those features:

More information about penalties or other scoring issues: It would be great to know if something is wrong, especially for people who don’t know much about SEO and lack experience, or for more experienced people like me to know if new sites have penalties or they are just crappy and new. It gets a little scary when a site goes from 50 visitors a day to 1 or 2.

Show links on your site that are broken: This is a big one! All there is out there (that I know of) is that Zenu software to check for broken links. EXTREMELY helpful for large sites so I don’t have to manually look at every single link. Problem is, Zenu always times out before it finishes a scan lol, it would be awesome to have this feature in webmaster tools to find what pages these bad links are. It could catch misspelled linking URLs as I make them.

Show causes of 404 errors: This goes hand in hand with finding broken links, especially if I don’t know what pages the broken links are located and it’s a huge site.

Option to “disavow” backlinks from or to a site: This would be an interesting tool because I would like to knock out some bad links that could be coming from hostile competitors or bad neighborhoods. At least I would have a little control over who links to me.

Fetch a page as Googlebot to verify correct behavior: It would be great to see a page through the eyes of Googlebot. The reason is because I had a site a LONG time ago when I was an inexperienced webmaster. My background was that of a repeated background image ON TOP of a white background. I had white text over this image. The problem is Googlebot probably saw this as white text over white background and I got a major penalty that lasted all year and I had to close up that business. I didn’t notice it for a few months because it came up as white text on a dark picture (which looked sweet by the way). I thought this traffic was “normal” getting 1 or 2 visitors per day but I didn’t know about penalties that whole year and realized that competitors with crappy looking sites and less content than mine were getting 100s of visitors per day. Again, this goes hand in hand with the “More information about penalties or other scoring issues” feature that would help indicate problems!

Those are the features that would help me out the most. Just thought I would throw it out there with my reasoning.

Best

Option to “disavow” backlinks from or to a site ,

because I want let you know that this must be stopped at ounce:

66.249.65.205 – - [31/Jan/2008:22:28:07 +0100] “GET /graph/Black-Smoker/?ref=SaglikAlani.Com HTTP/1.1″ 200 – http://www.light2art.de “-” “Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)” “-”

or how else can I stop this rumor?

Greetings Karl

I see that a geo target location tool has been added now – thanks to Matt and the Webmaster Tools team.

http://googlewebmastercentral.blogspot.com/2007/10/better-geographic-choices-for.html

Groovy

“Tell Google the correct country or language for a site” is another good point, in some countries web hosting is really expensive and people get web hosting abroad.

The ones I’d most like to see however are:
1. Tell Google a parameter doesn’t matter
2. Tell Google the correct country or language for a site
3. More information about penalties or other scoring issues
4. Tool to help move from one domain to a new domain

2. Option to “disavow” backlinks from or to a site (Without this isn’t there room for abuse from competitors?)

i mean its kind of rediculous when they dont answer contact requests, they dont say why sites get gutted and only point to a vague webmaster guideline… how about some reason and details why our site was gutted? or god forbid a way to fix them without waiting from an eternity to an infinite eternity to get the gutting to go away