The content on your website can be spell-checked at the time of writing. In Internet Explorer the IE Spell software can be installed (free for personal use, pay to register for commercial use). Firefox has spell-checking plugins which can be installed direct into the browser.
Audiences rate web content validity by many criteria. One of the criteria is that links within content are live. Checking links manually can be a slow and frustrating task. Xenu is a free utility for checking links in an entire website. Xenu produces reports showing broken and redirected links within the website.