I just read an article about common grammar mistakes that occur in blogs. I hope a lot of bloggers read it and it has a positive affect on blog grammar. Its always been one of my pet peaves. If your interested in improving your grammar, then their are many sites on the web to help out (i.e. Lynch, Guide to Grammar and Style).
PS: I should of mentioned that I taught English in Berlin for 5 years. So I consider myself somewhat an expert.