Hands down, I use Google Webmaster Tools but I recently got into using Live's Tools.
It's seemingly a slick interface but for me one of the best parts is how; under the "Keywords" tab you can enter a keyword phrase then they feed back the pages which meet that phrase and how those pages score PLUS they give you the Last Crawled date of each of those specific pages.
It appears there's only about a 1 day lag between the time you make a change and when they crawl it, supported by the "Last Crawled" information.
"Outbound Links" and "Backlinks" tabs show Page Score. Which as per Live its,
Your page score Provides a measurement of how authoritative Live Search views your page to be, with 5 green boxes being the highest rating and 5 empty boxes being the lowest. This is based on many of the same factors we use to determine Static Rank, but is not directly comparable.
I find useful information w/ this tool but I'm sure I'm not the first to post about it, but it's just another way to see how "engines" see the site, right?