Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
Website Grader - Grade your website's strengths and weaknesses in seconds.
Scrutiny - Scrutiny for Mac helps you manage and improve any number of websites. Link check, search, full website spell check, XML sitemap generator, SEO audit
PageSpeed Ninja - One-click page speed boost for WordPress
LinkChecker - LinkChecker is a free, GPL licensed website validator.
WebSite Auditor - The techie's SEO spider: find site issues other tools miss