It`s not much use if you have a nice site or blog, but, the English (assuming it`s an English language site of course), is of a poor standard.
So, check your spelling first, it doesn`t have to take long, but it`s worth it in the end if it gives a more polished result.
My favourite is
SpellCheck.net. Just Cut & Paste the text from your web page into it and it`ll highlight any potentailly misspelt words.
Dr. Watson will spell check a web page, and analyize the HTML, verifying the links, generating word counts, estimating download speeds, checking search enging compatability, and checking site popularity.