There are a lot of useful free tools out there - here is a selection of them.

• Keyword generator - free keyword suggestion tool from Wordtracker.
• W3C CSS validator - run your site through this checker to see if there are any CSS errors on your site, or run it through the HTML validator to check the markup validity.
• W3C also have a link checker to make sure there are no broken links on your site.
• Website optimizer - will check the speed of your site (a bit outdated, but fun non the less)
• Google ad planner - for certain sites, you can see what their traffic is (even if you're not planning ads!)
• Google analytics - official site from where you can follow the blog and get help with Google analytics.
• Lorem Ipsum - This lets you create psudo latin dummy text to use as a placeholder alternative to 'insert text here'.